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CBSE PATTERN SPECIALIST SINCE 2002 SUMMATIVE ASESSMENT- I CLASS XCBSE BOARD SAMPLE PAPERS 2012- 13 2012: 20012 RESULTS X & XII CBSECLASS X1)?ASMITA A GAIND? ??ENGLISH COMM.:???10 , MATHEMATICS : ? ? ? ??09? ? SCIENCE:?10 ? ? ? ? ? ? CGPA?9.82)RAJ HANMANT KATKAR ???? ?ENGLISH COMM.:? ? ?10 ? ?MATHEMATICS :? ??09? ? SCIENCE?:10 ? ? ? ? ? ?CGPA?9.8?3)Hemang PancholiMATHEMATICS:? ? ? 10?? ?CLASS XII (Sci)1)?KIRAN ASHOK SALUNKE??PHYSICS : 088???; ?CHEMISTRY?:086??; BIOLOGY:? 090 ? ? Total:85.2%2)? ? ?PRABODHINI .B. BHUMKAR??MATHEMATICS :?077?;?PHYSICS :?094?;CHEMISTRY : ?084 ? ?Total:84.8%?3)INDERJEET SINGH??PHYSICS: ?84 ;Total:83.2%?OVER ALL 100% Result! Thax. to all dedicated teacherSYLLABUS MATHEMATICS X SAI I. NUMBER SYSTEMS 11 ;II. ALGEBRA 23 ; III. G EOMETRY 17 ;IV TRIGONOMETRY 22 ; V STATISTICS 17 TOTAL 90BY;CBSE EXPERT AJAY KUMAR MISHRANote : This booklet contains mathematics Important formulae on next page.Sides )Algebra SOLUTIONS MATHEMATICS 2012-13 SAMPLE PAPER –ISolutions:1]One decimal place2]An odd integer3]Since -3 is the root of quadratic polynomial, we have(K - 1)(-3)2?+ 1 = 0?4]5]Median6]x = 3 sec2??- 1, y = tan2??- 2x - 3y = 3sec2??- 1 - 3tan2??+ 6= 3(sec2??- tan2) + 5= 3 + 5= 87]cos??+ cos2??= 1??1 - cos2??= cos?sin2??+ sin4?=??+ (1 - cos2?)2= cos??+ cos2?= 18]9]Since, 870 = 225??3 + 195225 = 195??1 + 30195 = 30??6 + 1530 = 15??2 + 0?HCF (870,225) = 1510]?x + y = 3?-x + y = 1ORSubtracting equation (1) from 3x -??= 5, we getFrom equation (1), x = 311]?are roots of x2?- (k + 6)x + 2(2k - 1)12]From?1 +?3 =?1 +?2??3 =?213]Cot??=??(given)=??=?=?14]C.Ifc.f.135 - 14044140 - 145711145 - 1501122150 - 155628155 - 160735160 - 165540Here, n = 40?Median class is 145 - 150Also, since highest frequency is 11, Modal class is 145 - 150.15]To prove 5 +??is irrational, let us assume 5 +??is rational.?We can find integers a and b where a, b are co-prime, b?Such that,?Now a, b are integers,??is rational.?is rational.Which is a contradiction. So 5 +??is irrational.ORLet us assume to the contrary, that?is a rational number.is rational.(n-1)+(n+1)-2?is rational2n+2?is rationalBut we know that?is an irrational numberSo 2n+2?is also an irrational numberSo our basic assumption that the given number is rational is wrong.Hence,is an irrational number.16]f(x) = x2?- 2x + 1Zeroes of f(x) are??,??Sum of zeroes???+???= 2 and??.??= 1Required polynomial = k(x2?- 4x + 4), where k is any integer.17]Let the length and breadth of the rectangle be x and y respectively.So the original area of the rectangle=xyAccording to question,(x+2)(y-2)=xy-28i.e.?xy-2x+2y-4=xy-282x-2y=24?...(i)Next,?(x-1)(y+2)=xy+33i.e.?xy+2x-y-2=xy+332x-y=35?..(ii)Now we need to solve (i) and (ii)From (ii) we get,y=2x-35substituting this value in (i) we get,2x-4x+70=24-2x=-46x=23substituting this value in (ii)we get,y=11So the length and breadth of the rectangle are 23 metres and 11 metres respectively.ORLet 40 % acids in the solution be x litresLet 60 % of other solution be y litresTotal Volume in the mixture = x + yGiven volume is 10 litresx + y = 10?---(i)Also,?So, 40 x + 60 y =500 or 2x+3y =25?…(ii)Solving (i) and (ii) we get x = y = 5 litres18]The system has infinitely many solution?Equating (1) and (2), we get a = 5bEquating (2) and (3), we get 2a - 4b = 6?On solving, we get b = 1 and a = 5.19]By BPT20]To prove AB? = AC? = 2AD? +?Draw?AE???BCIn ?ABD since??D > 90°???AB? = AD? + BD? + 2BD x DE …(1) (using Obtuse angle property) ?ACD = since??D < 90°AC? = AD? + DC? - 2DC x DE?…(2) (using acute angle property)Adding (1) and (2)AB? + AC? = 2(AD? + BD?)=2(AD? +??)Or AB? + AC? = 2(AD? + BD?)Hence proved.21]Given:?L.H.S. = (m? + n?) cos??OR22],?we haveleft023]CI50-6060-7070-8080-9090-100100-110Totalfi534p21327+pxi5565758595105fi?xi27519530085p19013652325+85pMean =??Substituting the values we get?86 =??86p + 2322 = 2325 + 85p?p = 324]Age in yrs. ( more than or equal to)0-1010-2020-3030-4040-5050-6060-70No. of persons (fi)1015252213105Since the maximum frequency is 25 and it lies in the class interval 20-30.Therefore, modal class = 20 - 30??= 20, h = 10, f0?= 15, f1?= 25, f2?= 22mode =???+= 20 +?= 20+7.69 = 27.69 years (approx.)25]If the number 15n?where n?N, were to end with a zero, then its prime factorisation must have 2 and 5 as its factors.But 15=5???315n?= (5???3)n?= 5n???3nSo Prime factors of 15n?includes only 5 but not 2Also from the Fundamental theorem of Arithmetic, the prime factorisation of a number is unique.Hence a number of the form 15n?where n?N, will never end with a zero.26]To solve the equations, make the table corresponding to each equation.x?1?2?3y420x4?1y04Now plot the points and draw the graph.Since the lines intersect at the point (?1, 4), so x = ?1 and y = 4 be the solution.Also by observation vertices of triangle formed by lines and x-axis are A (?1, 4),B (?3, 0) and C (4, 0).27]Let p(x) = x3?- 6x2?- 15x + 80Let say that we subtracted ax + b so that it is exactly divisible by x2?+ x - 12s(x)?= x3?- 6x2?- 15x + 80 - (ax + b)= x3?- 6x2?- (15 + a)x + (80 - b)Dividend = Divisor x Quotient + RemainderBut remainder = 0???Dividend = Divisor x Quotients(x) = (x2?+ x -12) x quotients(x) = x3?- 6x2?- (15 + a)x + (80 - b)x (x2?+ x - 12) - 7(x2?+ x - 12)= x3?+ x2?- 7x2?- 12x - 7x + 84= x3?- 6x2?- 19x + 84Hence, x3?- 6x2?- 19x + 84 = x3?- 6x2?- (15 + a)x + (80 - b)-15 - a = - 19???a = +4and?80 - b = 84???b = -4Hence if in p(x) we subtracted 4x - 4 then it is exactly divisible byx2?+ x -12.28]AD is the median of??ABC since D is mid-point of BC?BD = DC=?....(i)In right triangle?AEB,...Pythagoras?theorem=()+?Using Pythagoras theorem for right triangle AED and BE=BD-DE=+(....from (i)AB2=++?-2?-BC x DE +?Hence iven: A right triangle ABC right angled at B.To prove: that AC2?= AB2?+ BC2Construction:Let us draw BD?AC (See fig.)Proof?:Now,?ADB??ABC?(Using Theorem:If a perpendicular is drawn from the vertex of the right angle of a right triangle to the hypotenuse ,then triangles on both sides of the perpendicular are similar to the whole triangle and to each other)So,??(Sides are proportional)Or, AD.AC = AB2Also,?BDC??ABC?(Theorem)So,?Or, CD. AC = BC2Adding (1) and (2),AD. AC + CD. AC = AB2?+ BC2OR,?AC (AD + CD) = AB2?+ BC2OR,?AC.AC = AB2?+ BC2OR?AC2?= AB2?+ BC2Hence Proved.29]ABC??ADE (by AA Similarity)In right??AB2?= BC2?+ AC2?(by PT)?AB2?= 52?+ 122?= 25 + 144 = 169?AB = 13Subsisting AB = 13 cm, BC = 12 cm and AC = 5 cm in (1) andGetting DE =??and AE =?30]To prove:?Using the identity cosec2?A = 1 + cot2AL.H.S =?= cosecA + cotA= R.H.SOR=RHS31]LHS =??????= sin= RHS32]Hence, LHS = RHS.33]We can find frequency distribution table of less than type as following -Daily income(in Rs)(upper class limits)Cumulative frequencyLess than 12012Less than 14012 + 14 = 26Less than 16026 + 8 = 34Less than 18034 + 6 = 40Less than 20040 + 10 = 50Now taking upper class limits of class intervals on x-axis and their respective frequencies on y-axis we can draw its ogive as following -34]Class Interval0-66-1212-1818-2424-30Frequency4x5y1Cumulative frequency44+x9+x9+x+y10+x+yIt is given that total frequency N is 20So, 10+x+y = 20 i.e. x + y = 10?….(i)Given 50% of the observations are greater than 14.4.So median = 14.4, which lies in the class interval 12-18.= 12, cf = 4 + x, h = 6, f = 5, N = 20Median =?14.4 = 12 +?x 614.4 - 12 =?x6= 6 - x?x =4Now using equation, 10+x+y = 20, we get y = 6.Hence x =4 and y = 6.SAMPLE PAPER –IISolutions:1]?tan B??tan c =??=12]Number of zeros is one as the graph touches the x-axis at one point.3]3Median = Mode + 2 meanMedian =??=?=?4]SinceTherefore, lines are parallel.5]BC =?6]?Therefore, PN = 4.8 cm7]8]Let?Then, x=0.7777……?… (1)?Here ,the number of digits recurring is only 1,so we multiply both sides of the equation by 10.?… (2)Subtracting(1) from(2),we get9x=79]?-3 and -4 are zeroes of the polynomialSum of zeros = -3 - 4 = -7=Product of zeros = (-3) (-4) =??=?10]Let it possible 6n?ends with digit 0?6n?= 10?q(2??3)n?= 2??5??q2n??3n?= 2??5??q5 is a prime factor of 2n??3nWhich is not possible 2n??3n?can have only 2 and 3 are prime factors. Hence, it is not possible the number ends with digit 5.11]Marksfcf0 - 105510 - 30152030 - 60305060 - 8085880 - 10026N=Here, N=60?So, N/2=30The cumulative frequency is just greater than N/2=30 is 50 and the corresponding class is 30-60.Hence,30-60 is the median class.Therefore, l=30,f=30 ,F=20,h=30Now, Median=Median = 4012]Condition for infinitely many solution?(?)similarly,?k + 2 = 4?3k + 2 = 8k = 2?k = 2?k = 2 is the common solution.13]Sin(45 + 30) = sin 45o?cos 30o?+ cos 45o?sin 30oSin 75o?=?=?=?ORCosec =?AB =?Cot??+ tan??=?==?14]In?ABD and?ECFD =?F = 90oB =?C?By AA similarity,?ABD??ECF15]Let Rekha's Age be 'x'yearsAnd her mother's age be 'y' yearsy = 5x as per given data?… (1)After 5 yearsy + 5 = 3(x+5)y - 3x = 10?… (2)Solving (1) and (2) equation.Rekha's age = 5 yearsMother's age = 25 yearsORLet the two number be 5x, 6xTwo numbers are 40,48.16]Sin?=???tan??=?17]a=12?a+b=25?b=13?c=25+10=35?c+d=43?d=43-35=8?43+e=48?e=5f=48+2=5018]To calculate the mean, first obtain the column of mid value and then multiply the corresponding values of frequency and mid value.C.I.fMid value(x)fx0-100250100100-2003150450200-30052501250300-4002350700400-50034501350153850Here?and?, so the mean is given as.19]=?=?=?Simplifying we get, 1 + sec??. cosec?OR20]ADE??ABC?by AA similarity?…(1)21]Given p(x) = 6x3?+ 3x2?- 5x + 1a = 6, b = 3, c = -5 d = 1,r are zero.?=??=?22]Let??be rational and equal to?then??where a and b are co primes,??here a,b are integers?is rational .Therefore,?is rational???is rational?which is a contradiction?6 +??is an irrational numberORLet 5 -??be rational equal to?Then 5 -??=??a,b are integers?is rational which is a contradictionHence 5 -??is an irrational number23]In fig,?PQD,?Using Pythagoras?thm.PD2?= a2?- c2?…(1)Similarly in?PD2?= b2?- d2?…(2)From (1) and (2) a2?- c2?= b2?- d2?a2?- b2?= c2?- d2?(a + b) (a - b) = (c + d) (c - d)24]Multiply equation (1) by 3 and add in equation (2), we getUsing equation (1),y - 2 = 3?y = 5Hence?x = 4, y = 5.25]Let 5q + 2, 5q + 3 be any positive integers(5q + 2)2?= 25q2?+ 20q + 4= 5q (5q + 4) + 4?is not of the form 5q + 2Similarly for 2nd(5q + 3)2?= 25q2?+ 30q + 9=5q(5q+6)+ 9 is not of the form 5q+3So, the square of any positive integer cannot be of the form5q+2 or 5q+3For any integer q26]Statement?If a line is drawn parallel of one side of a triangle to intersect the other two sides in distinct points, the other two sides are divided in the same ration.Given:A triangle ABC in which a line parallel to side BC intersects other two sides AB and AC at D and E respectively (see fig.)To prove?that?Construction:Let us join BE and CD and then draw DM??AC and EN??AB.Proof:Now, area of?left0Note that?BDE and DEC are on the same base DE and between the same parallels BC and DE.So, ar(BDE) = ar(DEG)Therefore, from (1), (2) and (3), we have:OR?Statement: The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.Given:??ABC ~??PQR To Prove:??Construction: Draw AD?BC and PS?QR?Proof:???ADB ~??PSQ?(AA)?Therefore,??… (iii)?But??ABC ~??PQR?Therefore,??… (iv)?Therefore,??Therefore,??From (iii)27]2 sec2?- sec4?- 2sec2?+ cosec4= 2 (1 + tan2) - (1 + tan2)2?- 2(1 + cot2) + (1 + cot2)2= (1 + tan2) (1 - tan2) - (1 + cot2) (1 - cot2)= 1 - tan4?-1+cot4= cot4?- tan428]We have,x-y=12x+y=8Graph of the equation x-y=1:We have,x-y=1?=>y=x-1 and x=y+1Putting x=0,we get y=-1Putting y=0,we get x=1Thus, we have the following table for the points on the line x-y=1:x01y-10Plotting points A(0,-1),B(1,0) on the graph paper and drawing a line passing through them,we obtain the graph of the line represented by the equation x-y=1 as shown in fig.Graph of eqn 2x+y=8:We have,2x+y=8?=>y=8-2xPutting x=0,we get y=8Putting y=0,we get x=4Thus,we have the following table giving two points on the line represented by the equation 2x+y=8.x04y80Plotting points C(0,8) and D(4,0) on the same graph paper and rawing a line passing through them, we obtain the graph of the line represented by the equation 2x+y=8 as shown in fig.Clearly ,the 2 line intersect at P(3,2).The area bounded by these 2 lines and y-axis is shaded in the given fig.29]=?=?OR?30]MarksFrequency25 - 35535 - 451045 - 552055 - 65965 - 75675 - 852Total52Here the maximum frequency is 20 and the corresponding class is 45-55.So,45-55 is the modal class.We have,l=45,h=10,f=20,Mode =??+?Mode=49.731]Let p(x) = x3?+ 2x2?+ kx + 3Then using Remainder theoremp(3) = 33?+ 2??32?+ 3k + 3 = 21?k = -9Quotient of p(x) is x2?+ 5x + 6Hence, x3?+ 2x2?- 9x + 3 = (x2?+ 5x + 6) (x - 3) + 21?x3?+ 2x2?-9x - 18 = (x - 3) (x + 2) (x + 3)All the zeros of p(x) are 3,-2,-3.32]Given:??ABC is a right angled triangle,??B = 900To prove: AB2?+ BC2?= AC2Construction: Drop a perpendicular BD on the side AC.Proof:?From triangle ADB and triangle ABC,?We can re-write as,?AC × AD = AB2Also, triangle BDC is similar to triangle ABC.Equating the proportional sides of the similar triangles BDC and ABC,?AC × CD = BC2Now adding this to the equation that we had obtained,AC × AD + AC × CD = AB2?+ BC2??AC × (AD + CD) = AB2?+ BC2??AC × AC = AB2?+ BC2??AC2?= AB2?+ BC233]LHS=?= Cos A + sin A = RHS34]We first prepare the cumulative frequency distribution table by less than method as given below:Marks?no. of students?marks less than?cumulative frequency0-10?7?10?710-20?10?20?1720-30?23?30?4030-40?51?40?9140-50?6?50?9750-60?2?60?100Other than the given class intervals ,we assume a class-10-0 before the first class interval 0-10 with zero frequency.Now, we mark the upper class limits along X-axis on a suitable scale and the cumulative frequencies along Y-axis on a suitable scale.Thus, we plot the points(0,0),(10,7),(20,17),(30,40),(40,91),(50,97)and(60,100).Now, we join the plotted points by a free hand curve to obtain the required ogive.SAMPLE PAPER –IIISolutions:1]2]Zeroes of a polynomial are the x- coordinates of the points where its graph crosses or touches the X- axis. Graph of y = p(x) intersects the X-axis at 4 points. Therefore, the polynomial p(x) has 4 zeroes3]Range is not a measure of central tendency.4]7×11×13+13 +13 x 2?= 13(7×11 + 1+2) = 13(80)5]Smallest composite number= 4 and the smallest prime number=2.?HCF of 2 and 4 = 2.6]For the system of linear equations:?a1x + b1y + c1?= 0, anda2x + b2y + c2?= 0 to have no solution?For the system of equations?3x + y = 1,(2K - 1) x + (K - 1) y = 2K + 1 a1?=3, b1?= 1, c1?= 1, anda2?= 2K-1?b2?= K-1?c2?= 2K+1This gives K=2.7]Given that 3cot A=4, we have, cot A=Then, tan A=Now, (1-tan2A)= 1-?=?And, ( 1+tan2A)?= 1+??=?THerefore,?8]tan A=cot Btan A=tan(900-B)A=900-B or A+B=9009]In?ADC, AD2?= AC2?- CD2In?ABD, AD2?= AB2?- DB2AB2?- B2?= AC2?- CD2?AB2?+ CD2?= AC2?+ BD210]120 = 23??3??5144 = 24??32LCM = 24??32??5 = 720HCF = 23??3 = 2411]3x + 4y = 104x - 4y = 4x?= 2x - y = 1??y = x - 1 = 2 - 1 = 1The solution x = 2, y = 112]We know that sin2??+ cos2??=1 Taking cube of both sides (sin2??+ cos2??)3?=13(sin2??)3?+ (cos2?)3?+ 3 sin2??.cos2??(sin2??+ cos2?)= 1Therefore, sin6??+ cos6??+ 3sin2?cos2?=113]MarksNo. of students0 - 1010 - 2020 - 3030 - 4040 - 50276510Total3014]Let p(x) = x3?+ ax2?+ b x + 16g(x) = x - 2?is a factor of p(x)???p(2) = 0so, p(2)?= 8 + 4a + 2b + 16 = 0= 4a + 2b = -24= 2a + b = -12?(i)Also?a -b?= 16?(ii)Solving (i) and (ii)3a = 4???a =?ORGiven polynomial p(x) = ax2?- 5x + cSum of zeroes m + n =?Product of zeroes mn =?Given: m + n = mn = 1015]Modal Class = 20-30???= 20, f0?= 12, f1?= 32, f2?= 20, h = 10 Mode =??Mode =??= 26.2516]Construction - draw AE??BCIn right triangle?AEB and AECAB2?+ AC2?= BC2?+ AE2?+ EC2?+ AC2?= 2AE2?+ (BD - ED)2?+ (ED + DC)2= 2AE2?+ 2ED2?+ BD2?+ DC2AB2?+ AC2?= 2AE2?+ 2ED2?+ 2BD2= 2 [AE2?+ ED2] + 2BD2= 2 (AD2?+ BD2)17]LHS =?=??= 2 cosec A = RHS18]Let the fraction be:?According to the questionx + y = 8On solving we get x = 3, y = 5The fraction is?ORLet the tens and units digits of the number be x and y respectively then7(10x + y) = 4 (10y + x)70x + 7y = 40y + 4x66x = 33yy = 2xAlso, y - x = 3On solving, x = 3, y = 6Number = 36.19]Let??be a rational numberLet??=??= p11q2?= p211 divides p2?hence 11 divides P.Let p = 11c?11q2?= 121 c2Or q2?= 11c211 divides q2?Hence 11 divides qFrom (1) and (2) p and q have a common factor 11 which contradicts our assumption.??is irrationalORLet 2?- 7 is rational??=?Since p and q are integer??is rational??is rationalBut we have that??is irrational?our assumption is wrong. Hence 2?- 7 is irrational.20]Class IntervalFrequency0 - 207720 - 4081540 - 60122760 - 80103780 - 100845100 - 120550Total50Median class?40 - 60=?40, f = 12 CF = 15 h = 20Median =??+?= 40 +?= 40 +?= 40 +?= 56.7ORAge (in Years)No. of people fiValue xifixi0 - 20151015020 - 40f13030f140 - 602150105060 - 80f27070f280 - 10017901530Total1002730 + 30f1 + 70 f253 + f1 + f2 = 100f1 + f2 = 47?…(1)53 =?5300 - 2730 = 30f1 + 70f230f1 + 70f2 = 2570Or 3f1 + 7f2 = 257?…(2)?f1 + f2 = 47f2 = 47 - 29 = 1821]In?ABC and?DACBAC =?ADCC =?C22]LHS =?= 1 + cos A=?=??OR?23]p(x) = x3?- 3x2?+ x + 2g(x) = ?q(x) = x - 2?r(x) = -2x + 4p(x) = g(x) + r(x)x3?- 3x2?+ x + 2 = g(x) (x - 2) - 2x + 4g(x) =?=?= x2?- x + 124]The system has infinitely many solutions:?Equating (1) and (2), we get a = 5bEquating (2) and (3), we get 2a - 4b = 6On solving, we get b = 1 and a = 5.25]If a and b are one two positive integers. Then a = bq + r, 0??r??b Let b = 3 Therefore, r = 0, 1, 2 Therefore, a = 3q or a = 3q + 1 or a = 3q + 2?If a = 3q a2?= 9q2?= 3(3q2) = 3m or where m = 3q2?a = 3q + 1 a2?= 9q2?+ 6q + 1 = 3(3q2+ 2q) + 1 = 3m + 1 where m = 3q2?+ 2q or a = 3q + 2 a2?= 9q2?+ 12q + 4 = 3(3q2?+ 4q + 1) + 1= 3m + 1, where m?3q2?+ 4q + 1Therefore, the squares of any positive integer is either of the form 3m or 3m + 1.26]CI1-44-77-1010-1313-1616-19fi630401644xi2.55.58.511.514.517.5Average most suitable here is the Mode because we are interested in knowing the length of surname for maximum no. of peopleSince the maximum frequency is 40 and it lies in the class interval 7-10.Therefore, modal class = 7-10?= 7, h=3, f0=30 , f1=40 , f2=16Mode =?= 7+= 7 +.88 = 7.88 years(approx.)27]LHS =?????= tan??+ cot??+ 1 = RHSORLHS=(cosec A - sin A) (sec A - cos A) (tan A + cot A)==1= RHS28]Basic proportionality theoremStatement?If a line is drawn parallel of one side of a triangle to intersect the other two sides in distinct points, the other two sides are divided in the same ratio.Given:A triangle ABC in which a line parallel to side BC intersects other two sides AB and AC at D and E respectively (see fig.)To prove?that?Construction:?Let us join BE and CD and then draw DM??AC and EN??AB.Proof:Now, area of?Note that?BDE and DEC are on the same base DE and between the same parallels BC and DE.So, ar(BDE) = ar(DEG)Therefore, from (1), (2) and (3), we have :?Hence proved.ORPythagoras Theorem?: Statement:In a right angled triangle,the square of the hypotenuse is equal to the sum of squares of the other two sides.Given: A right triangle ABC right angled at B.To prove: that AC2?= AB2?+ BC2Construction:Let us draw BD?AC (See fig.)Proof?:Now,?ADB??ABC?(Using Theorem: If a perpendicular is drawn from the vertex of the right angle of a right triangle to the hypotenuse ,then triangles on both sides of the perpendicular are similar to the whole triangle and to each other)So,??(Sides are proportional)Or, AD.AC = AB2?(1)Also,?BDC??ABC?(Theorem)So,?Or, CD. AC = BC2Adding (1) and (2),AD. AC + CD. AC = AB2?+ BC2OR,?AC (AD + CD) = AB2?+ BC2OR,?AC.AC = AB2?+ BC2OR,?AC2?= AB2?+ BC2Hence proved.29]m2?- n2?= (m + n) (m - n)=?= 2 tan??. 2 sin?= 4 tan??. sin?= 4?= 4?= 4?= 4?= 4?30]Let p(x) = x3?- 6x2?- 15x + 80Let say that we subtracted ax + b so that it is exactly divisible byx2?+ x - 12s(x) = x3?- 6x2?- 15x + 80 - (ax + b)= x3?- 6x2?- (15 + a)x + (80 - b)Dividend = Divisor x Quotient + RemainderBut remainder = 0???Dividend = Divisor x Quotients(x) = (x2?+ x -12) x quotients(x) = x3?- 6x2?- (15 + a)x + (80 - b)x (x2?+ x - 12) - 7(x2?+ x - 12)= x3?+ x2?- 7x2?- 12x - 7x + 84= x3?- 6x2?- 19x + 84Hence, x3?- 6x2?- 19x + 84 = x3?- 6x2?- (15 + a)x + (80 - b)-15 - a = - 19???a = +4and?80 - b = 84???b = -4Hence if in p(x) we subtracted 4x - 4 then it is exactly divisible byx2?+ x -12.31]We have to solve the pair of equations graphically2x + 3y = 11?… (1)2x - 4y = -24?… (2)For (1)X14-2y315For (2)X-120-10y061point of intersection x = -2,?= 5The triangle formed is shaded as?ABC coordinates areA (-2,5) B (-12,0) C(5.5,0).32]Class IntervalFrequency0 - 15615 - 30730 - 45f145 - 601560 - 751075 - 90f2Total51Mode = 55?(Given)?Modal Class 45 - 60?= 45, fo = f1 and?f1 = 15f2 = 10 h = 1538 + f1 + f2 = 51f1 + f2 = 51 - 38f1 + f2 = 13?…(1)55 = 45 +?10 =?200 - f1 = 225 - 15f15f1 = 25f1 = 5f1+f2=13f2=13-5=8The missing frequencies are 5 and 8.33]?Statement: The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.Given:??ABC ~??PQR To Prove:??Construction: Draw AD?BC and PS?QR?Proof:???ADB ~??PSQ?(AA)?Therefore,??… (iii)?But??ABC ~??PQR?Therefore,??… (iv)?Therefore,??Therefore,??From (iii)34]LHS =??RHS =???=?tan?Hence, LHS = RHS.SAMPLE PAPER –IVolutions:1]Mode = 3 median?-?2 mean2]3]4]A rational number can be expressed as a terminating decimal if the denominator has factors 2 or 5.5]9 cm 5 cm 7cm cannot form the sides of a right triangle as the Pythagoras theorem is not satisfied in this case.6]For the system of equations:?2x + 3y = 74x + 6y = 5we have?Since??is the condition for no solution and henceinconsistent?system of equations.7]Since??is a root of the equation?(p + q)2?x2?-?2 ( p + q) x + k =0?So,?(p + q)2??-?2 ( p + q ) .??+ k = 0?????????????????25?-?10 + k = 0?????????????????k = -158]9]HCF??LCM = Product of the number9??90 = 18??xx =?10]Monthly income range(In Rs.)No. offamilies10000-13000513000-160001616000-190001919000-220001722000-250001825000-2800015No. of families having income range (in Rs.) 16000-19000 is 19.?From the graph it is clear that median is 4.11]LHS = 1 +?= 1 +?= 1 + cosec??- 1 = cosec??=??= RHS12]Since??A =??B, AC = BC … (1)Also AD = BE … (2)Subtracting (2) from (1),?AC - AD = BC - BE?DC = EC?… (3)From (2) and (3), we haveTherefore, DE || AB?by converse of BPT.13]One of the zero =- 15Sum of the zeroes = 42?Other zero = 42 + 15 = 57?Product of the zeroes = 57??-15 = 855?The quadratic polynomial is x2?-?42x?-?855ORLet p(x) = 2x2?-?4x + 5?? +???= (??+??)? - 2??Substituting the values, we get =??? +???= -114]For no solution:?3p?-?3 = 2p?-?1?p = 215]Modal class?-?30?-?40?= 30?fo?= 12?fi?= 20 f2 = 11 h = 10Mode =??+?= 30 +?= 30 +?16]Construction: Draw PA??QR and SB??GR?(As one angle is 90 degrees and one is vertically opposite angles)?From (1) and (2), we get17]Let 5 + 7??is rational number5 + 7??=?7??=??=?Since p and q are integers?a rational number?is rationalBut we know that??is rational?Out assumption is wrong?5 +??is irrational.?ORLet??be a rational numberLet??= p/q where q??0, p and q are integers and?coprime.7 q2?= p27 divides pLet p = 7m7q2?= 49 m2Q2?= 7m2?7 divides q2?7 divides q?7?divides?p and q both.Which is a contradiction for the that p?and q?are co-prime.18]LHS =?=??= sin A?cos?AHence, LHS = RHS.19]The polynomial?p(x) can be divided by the polynomial?g(x) as follows:Quotient =?x?-?3Remainder = 7x?-?920]Class IntervalFi?frequencyMid value xiFixi30?-?402357040?-?5034513550?-?6085544060?-?7066539070?-?8067545080?-?9038525590?-?100295190Total301930Mean =?ORDaily expenses (in Rs)No, of familiesC.F20?-?406640?-?6091560?-?80112680?-?1001440100?-?1202060120?-?1401575140?-?1601085160?-?180893180?-?2007100Total100Median class?-?100?-?120f = 20?cf?= 40 h = 20 l = 100Median =?= 100 +?= 100 + 10 = 11021]Construction: - Draw AE??BCIn right triangle AEBAB2?= AE2?+ BE2= AE2?+ (BD + DE)2= AC2?-?DE2?+ BD2?+ DE2?+ 2BD.DE= AD2?+??BC2?+ 2???BC???BC= AD2?+??BC29AB2?= 9AD2?+ 2BC29AB2?-?2AB2?= 9AD2??AB = BCOr 9AD2?= 7AB222]Let the speed of?Ritu?in still water and the speed of stream be?x?km/h and?y?km/h respectively.Speed of?Ritu?while rowing upstream =??km/hSpeed of?Ritu?while rowing downstream =??km/hAccording to the question,Adding equations (1) and (2), we obtain:Putting the value of?x?in equation (1), we obtain:y?= 4Thus,?Ritu’s?speed in still water is 6 km/h and the speed of the current is 4 km/h.ORLet the speed of train and bus?be?u?km/h and?v?km/h respectively.According to the question,Let??and?The given equations reduce to:Multiplying equation (3) by 10, we obtain:Subtracting equation (4) from equation (5), we obtain:Substituting the value of q in equation (3), we obtain:Thus, the speed of train and the speed of bus are 60 km/h and 80 km/h respectively.23]Given: sin???????????????????+?cos???????????????????= m and sec??????????????????+cosec???????????????????= nConsider,L.H.S. = n?=?=?=?24]Let the cost of one T-shirt be Rs x and that of one jacket be Rs y.According to given condition2x+y=625?…(i)3x+2y=1125?…(ii)Multiplying (i) by 2 we get4x+2y=1250?…(iii)Subtracting (ii) from (iii) we get,x=125Substituting this value of x in (i) we get250+y=625???????????????????y=375Therefore cost of one T-shirt is Rs125 and the cost of one jacket is Rs 375.25]Let a and b be any positive Integersa = b + r, 0??r <bLet b = 6?Thes?r = 0,1,2,3,4,5Where r = 0, a = 6m + 0 = 6m. which is evenWhere r = 1?a = 6m + 1?oddWhere r = 2?a = 6m + 2?evenWhere = 3?a?-?6m + 3?oddWhere r = 4?a = 6m + 4?evenWhere = 5?a?-?6m + 5?odd?All positive even integers?are of?the from?6m, 6m + 2 or 6m + 4.26]We have5 + f1 + 10 + f2 + 7 + 8 = 50f1 + f2 = 20f1 = 20?-?f2C.IfiXifixi0?-?205105020?-?40fi3030fi40?-?60105050060?-?8020?-?fi701400?-?70fi80?-?100790630100?-?1208110882Mean =?Therefore, f2?= 20 - 8 =12.27]In??…(1)Similarly???…(2)From (1) and (2)?xy?=?xz?+?yzDividing by xyz28]q =?Consider,q (p2?-?1)=?= 2p = RHS29]Since =?Zeroes of the given polynomial(x +??) (x -??) will be a factorOr x2?= 2 will be a factorLong division.2x2?- 3x+ 1 = 2x2?-?2x?-?2x + 1= 2x (x- 1)?-?1(x?-?1)= (2x?-?1) (x- 1 )?The other zeroes are??and 1.30]On dividing the numerator and denominator of?lts?by?cos??, we getOR=?31]Pythagoras Theorem: Statement: In a right angled triangle, the square of the hypotenuse is equal to the sum of squares of the other two sides.Given: A right triangle ABC right angled at B.To prove: that AC2?= AB2?+ BC2Construction: Let us draw BD??AC (See fig.)Proof?:Now,??ADB???ABC?(Using?Theorem:If?a perpendicular is drawn from the vertex of the right angle of a right triangle to the hypotenuse ,then triangles on both sides of the perpendicular are similar to the whole triangle and to each other)So,??(Sides are proportional)Or, AD.AC = AB2Also,??BDC???ABC?(Theorem)So,?Or, CD. AC = BC2Adding (1) and (2),AD. AC + CD. AC = AB2?+ BC2OR,?AC (AD + CD) = AB2?+ BC2OR,?AC.AC = AB2?+ BC2OR?AC2?= AB2?+ BC2ORStatement:Ratio?of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.Given: Two triangles ABC and PQR such that?To prove?:?Proof?For?finding the areas of the two triangles, we draw altitudes AM and PN of the triangles.Now,?ar?And?ar?(PQR) =?So,?Now, in??B =??Q?(As?And??m =??n?(Each is of 90o)So,??(AA similarity criterion)Therefore,?Also,?So,?Therefore,??[from (1) and (3)]=??[From (2)]=?Now using (3), we get32]The given cumulative frequency distributions of less than type is?-Weight(in kg)upper class limitsNumber of students(cumulative frequency)Less than 380Less than 403Less than 425Less than 449Less than 4614Less than 4828Less than 5032Less than 5235Now taking upper class limits on?x-axis and their respective cumulative frequency on?y-axis we may draw its?ogive?as following?-Now mark the point A whose ordinate is 17.5 its?x-coordinate is 46.5. So median of this data is 46.5.33]x?-?y?+ 1 = 0???????????????????x?=?y?-?1Three solutions of this equation can be written in a table as follows:x012y1233x?+ 2y?-?12 = 0???????????????????Three solutions of this equation can be written in a table as follows:x420y036Now, these equations can be drawn on a graph. The triangle formed by the two lines and the x-axis can be shown by the shaded part as:34]We have= Cos (90o?-?50o?-??)?-?cos?(40o?-??) +??SAMPLE PAPER –VSolutions:1]Let x1,x2,x3……..,x12?be the 12 values of the given data. Let the 13th?observation be?x13.x1+x2+x3……..+x12?= 12x19.25 = 231x1+x2+x3……..,x12+x13= 13x20=260(x1+x2+x3……..+x12)+x13= 260x13=260-231 = 292]Given, triangle ABC is right angled at C. Therefore,A+B=90o?or A=90o-B1+cot2A = 1 + cot2(90o-B) = 1+tan2B = sec2B3]A real number is an irrational number when it has a non terminating non repeating decimal representation.4]x2?+2x+1= (x+1)2??x = -1? = ?=?-11/ ??and?1/??are also -1.?1/ ? + 1/? = -25]Since the x-axis y=0 does not intersect y=-7 at any point.6]Since?.7]Because cosec 90°=1, others are not defined.8]9]If a and b are one two positive integers. Then a = bq + r, 0??r??b Let b = 3 Therefore, r = 0, 1, 2 Therefore, a = 3q or a = 3q + 1 or a = 3q + 2?If a = 3q a2?= 9q2?= 3(3q2) = 3m or where m = 3q2?a = 3q + 1 a2?= 9q2?+ 6q + 1 = 3(3q2?+ 2q) + 1 = 3m + 1 where m = 3q2?+ 2q or a = 3q + 2 a2?= 9q2?+ 12q + 4 = 3(3q2?+ 4q + 1) + 1?= 3m + 1 where m?3q2?+ 4q + 1?Therefore, the squares of any positive integer is either of the form 3m or 3m + 1.10]Given polynomial P(x) = x4?+ 2x3?- 2x2?+ x -1Let g(x) must be added to it.So, number to be added=-(-x+ 2) = x - 211]For infinite number of solution,ConsiderAgain,12]AC2?= AD2?+ CD2?… (2)[By Pythagoras theorem](1) - (2) gives,Hence proved.13]ORConsider,7 sin2???+ 3 cos2???= 47Sin2??+ 3 (1 - sin2?) = 4?7Sin2??+ 3 - 3sin2= 44Sin2??= 1?Sin?=?Thus,?Sec 30o?+ Cosec30o?=?14]Class IntervalCumulative FrequencyMore then 50More then 60More then 70More then 80More then 90More then 102108958063421915]Let 3 -??be a rational number.3 -??=??[ p,q are integers, 2??0]Here,LHS = Rational No.RHS = irrational No.But, Irrational no??Rational no?our assumption is wrong??is an irrational.ORLet us assume to the contrary, that?is a rational number.is rational.(n-1)+(n+1)-2?is rational2n+2?is rationalBut we know that?is an irrational numberSo 2n+2?is also an irrational numberSo our basic assumption that the given number is rational is wrong.Hence,is an irrational number.16]?… (1)?… (2)Multiplying (1) with a and (2) with b, we getFrom (1), bx + ab = 2abbx = ab?x = aHence, x = a and y = b.17]C.IFiXiFi.?.Xi10 - 205157520 - 303257530 - 4043514040 - 50F4545f50 - 6025511060 - 7066539070 - 80137597533+f1765+45fMean =?ORC.Ifixidifidi100 - 1504125-2-8150 - 2005175-1-5200 - 2501222500250 - 300227512300 - 350232524-7Where:?18]Let us assume that Prema invests Rs x @10% and?Rs y @8% in the first year.We know thatInterest =?ATQ,+=1640??10x + 8y = 164000?…(i)After interchanging,+=1600we get 10y+8x=1600008x+10y=160000?...(ii)Adding (i)?and?(ii)18x+18y=324000??x + y = 18000?... (iii)Subtracting (ii) from (i),2x-2y=4000??x - y = 2000?...(iv)Adding (iii) and (iv)2x=20000??x = 10000.Substituting this value of x in (iii)y=8000So the sums invested in the first year at the rate 10% and 8% are Rs 10000 and Rs 8000 respectively.ORSolving (1) and (2), we getx = 30 y = 6.19]Let??is one zero.??= 7?is another zero then?+ 7?=?8?=????=??and??=?Now,20]The two angles??and???being the acute angles of a right triangle, must be complementary angles.So,?Substituting,??in above equation21]Now, AP + AQ = 120 + 60 = 180 cm22]23]Let the area of triangle =x sq unitsArea of trapezium = 3x sq unitsArea triangle ABC = x + 3x = 4x?sq unitsNow,Consider triangles AED and ABC,ED ll BC...given?AED =??ABC?Corresponding angles?A =??A?Common?AED ~ ?ABC?[By AA rule]=(since Ratio of areas of two similar triangles is equal to ratio of square of corresponding sides)So?24]C.IFCf9.5 - 19.52219.5 - 29.54629.5 - 39.581432.5 - 49.592349.5 - 59.542759.5 - 69.522969.5 - 79.5130Here,?l = 39.5 c.f =?14 f = 9 h = 10M = 39.5 +?25]Given 2 and 3 are the zeroes of the polynomial.Thus(x - 2) (x - 3) are factors of this polynomial.4x4?- 20x3?+ 23x2?=5x - 6 = (x2?- 5x + 6) (4x2?- 1)Thus, 4x4?- 20x3?+ 23x2?+5x-6=(x - 2) (x - 3) (2x - 1) (2x + 1)Therefore, 2,3,?26]Given: A triangle ABC in which a line parallel to side BC intersects other two sides AB and AC at D and E respectivelyTo prove?that?Construction: Let us join BE and CD and then draw DM??AC and EN??AB.Proof: Now, area of?left0Note that?BDE and DEC are on the same base DE and between the same parallels BC and DE.So, ar(BDE) = ar(DEG)Therefore, from (1), (2) and (3), we have :ORGiven: A right triangle ABC right angled at B.To prove: that AC2?= AB2?+ BC2Construction: Let us draw BD?AC (See fig.)Proof:Now,?ADB??ABC?(Using Theorem: If a perpendicular is drawn from the vertex of the right angle of a right triangle to the hypotenuse ,then triangles on both sides of the perpendicular are similar to the whole triangle and to each other)So,??(Sides are proportional)Or, AD.AC = AB2?… (1)Also,?BDC??ABC?(By Theorem)So,?Or, CD. AC = BC2?… (2)Adding (1) and (2),AD. AC + CD. AC = AB2?+ BC2OR,?AC (AD + CD) = AB2?+ BC2OR,?AC.AC = AB2?+ BC2OR?AC2?= AB2?+ BC2Hence proved.27]ORDividing numerator and denominator of LHS by sin, we get28]29]Let the number of girls and boys in the class be x and y respectively.According to the given conditions, we have:x?+ y = 10x?- y = 4x?+ y = 10???x = 10 - yThree solutions of this equation can be written in a table as follows:x546y564x?- y = 4???x = 4 + yThree solutions of this equation can be written in a table as follows:x543y10-1The graphical representation is as follows:From the graph, it can be observed that the two lines intersect each other at the point (7, 3).So, x = 7 and y = 3.30]We can obtain cumulative frequency distribution of more than type as following:Production yield(lower class limits)Cumulative frequencymore than or equal to 50100more than or equal to 55100 - 2 = 98more than or equal to 6098 - 8 = 90more than or equal to 6590 - 12 = 78more than or equal to 7078 - 24 = 54more than or equal to 7554 - 38 = 16Now taking lower class limits on x-axis and their respective cumulative frequencies on y-axis we can obtain its ogive as following.31]?Statement: The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.Given:??ABC ~??PQR To Prove:??Construction: Draw AD?BC and PS?QR?Proof:???ADB ~??PSQ?(AA)?Therefore,??… (iii)?But??ABC ~??PQR?Therefore,??… (iv)?Therefore,??Therefore,??From (iii)32]Hence, L.H.S = R.H.S33]Let 5q + 2, 5q + 3 be any positive integers(5q + 2)2?= 25q2?+ 20q + 4= 5q (5q + 4) + 4?is not of the form 5q + 2Similarly for 2nd(5q + 3)2?= 25q2?+ 30q + 9=5q(5q+6)+ 9 is not of the form 5q+3So, the square of any positive integer cannot be of the form5q+2 or 5q+3For any integer q34]MarksFrequency25 - 35535 - 451045 - 552055 - 65965 - 75675 - 852Total52Here the maximum frequency is 20 and the corresponding class is 45-55.So,45-55 is the modal class.We have,l=45,h=10,f=20,Mode =??+?Mode=49.7SOLUTIONS SCIENCE 2012-13 SAMPLE PAPER –ISolutions:1]Y – Diamond and Z – Graphite2]1/253]Sometimes there is a lack of oxygen in our muscle cells hence the pyruvate breaks down to form lactic acid which builds up in our muscles during sudden activity and causes cramps.4]Plaster of Paris is calcium sulphate hemihydrates. It is obtained by heating gypsumUses:- (1)?Plastering fractured bones(2)?statues, toys etc.5]It is a double displacement and precipitation reaction.6]Plant kept in continuous light will live longer, because it will be able to produce oxygen required for its respiration by the process of photosynthesis.7]Maximum current through resistor?A = 3AThus the maximum current through resistors B and C each?8]The following events occur during photosynthesis:(i) Absorption of light energy by chlorophyll.(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.(iii) Reduction of carbon dioxide to carbohydrates9]The steps involved in reflex action are:(i) Receptors receive the stimulus(ii) Nerve cells takes the stimulus, converts it into electrical signal and passes it through sensory nerve.(iii) The impulse passes through spinal cord where it gets transmitted through relay neuron and it passes further through motor neuron to the effector organ, i.e. muscles.10]11](a) Silver chloride on exposure to sunlight may decompose as per the following reaction.Therefore, it is stored in dark coloured bottles.(b) Calcium oxide reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat12](a)?(b)?13]In absence of litmus paper a reagent phenolphthalein can be used. The solution which gets pink colour with phenolphthalein is base other is acid.14]A stimulus received by a neuron travels through it in the form of an electrochemical disturbance. When an electrical signal reaches the axonal end of one neuron, it releases chemical substance called neurotransmitter that cross the synapse and move towards the dendritic end of next neuron generating another electrical singal. A narrow fluid filled space, called synaptic cleft occurs between the two neurons. An impulse travels through the neurons only in one direction because the neurotransmitter releases only on one side of the synapse.15](a)(b)?16]The various plant hormones are auxin, gibberellin, cytokinin and abscisic acid. Functions of plant hormones:(a)?Auxin - It helps the cells to grow longer at shoot tips.(b)?Gibberellin – Growth of stem.(c)?Cytokinin – Promotes cell division.(d)?Abscisic acid – Inhibits growth in plants17]The thumb in right hand rule indicates the direction of current in the straight conductor held by curled fingers, whereas the Fleming's left-hand rule gives the direction of force experienced by current carrying conductor placed in an external magnetic field.18]Hints – Biomass: Plant and animal wastes. Give description of biogas plant with the following diagram.19](a)A current carrying conductor produces a magnetic field around it. When it interacts with magnetic field it experiences a force. Direction of the force depends upon direction of current and that of magnetic field.Fleming's left hand rule. State the rule.(b)The deflection will increase. As the magnetic field produced around the conductor is proportional to the current flowing through the wire.ORa)?The earth wire, which has insulation of green colour, isusually connected to a metal plate deep in the earth near the house.This is used as a safety measure, especially for those appliances thathave a metallic body, for example, electric press, toaster, table fan,refrigerator, etc. The metallic body is connected to the earth wire, whichprovides a low-resistance conducting path for the current. Thus, itensures that any leakage of current to the metallic body of the appliancekeeps its potential to that of the earth, and the user may not get a severeelectric shock.b) due to electromagnetic induction, there would be change in the magnetic field around the coil A and so will be around B . So?current will be induced in coil B.20](a) Baking powder (NaHCO3), salt A is commonly used in bakery products. On heating it forms sodium carbonate (Na2CO3), B and CO2?gas, C is evolved. When CO2?gas is passed through lime water it forms calcium carbonate (CaCO3), which is slightly soluble in water making it milky.A – NaHCO3B – Na2CO3C – CO2?gas(b)?Bleaching powder is used –(i)?for bleaching wood pulp in paper factories.(ii) for disinfecting drinking water to make it free of germs.OR(a) (i) Sulphuric acid + Zinc??Zinc sulphate + Hydrogen?H2SO4?(aq) + Zn(s)??ZnSO4?(aq) + H2?(g) (ii) Hydrochloric acid + Magnesium??Magnesium chloride + Hydrogen 2HCl (aq) + Mg (s)??MgCl2(aq) + H2?(g)(b)?A reaction in which an acid and base react with each other to give a salt and water is termed as neutralisation reaction. In this reaction, energy is evolved in the form of heat.(c)?Uses of washing soda:-(i) Sodium carbonate (washing soda) is used in glass, soap and paper industries.(ii) It is used in the manufacture of sodium compounds such as borax.21](a)?(b)?(c)?Na+?cation, Mg+2?cation O-2?anion(d)?Strong inter ionic attraction.OR(a)?Noble, highly malleable, ductile shinglustre(b)?Forms a protective layer of aluminium oxide(c)?Strong oxidizing agent oxides H2?to H2O(d)?Easy to reduce metallic oxide to metal(e)?Good conductor of heat, Non corrosive.22](a)?(b)?(c)?4V. Hint – V = IR =?= 4V(d)?No difference.Hint – Same current flows through each element in a series circuit.ORCurrent carrying loops behave like bar magnets and both have their associated lines of field. This modifies the already existing earth's magnetic field and a deflection result. Magnetic field has both direction and magnitude. Magnetic field lines emerge from N-pole and enter Spole. The magnetic field strength is represented diagrammatically by the degree of closeness of the field lines. Field lines cannot cross each other as two values of net field at a single point cannot exist. Only one value a unique net value, can exist. If in a given region, lines of field are shown to be parallel and equispaced, the field is understood to be uniform.23](a)(b) The digestion of carbohydrates (starch) starts in the mouth. The saliva has salivary amylase or ptyalin enzyme which acts on the starch and converts it into maltose sugar. The partially digested food reaches the stomach where the food gets mixed with gastric juice secreted by gastric glands. The gastric juice contains large quantities of mucus, HCl and pepsin. The enzyme pepsin acts on proteins and coverts them into peptones and proteoses. The gastric lipase emulsifies fats.Bile juice secreted from liver lipids into small droplets.Pancreas secretes pancreatic juice which contains the pancreatic amylase, trypsin and lipase. Pancreatic amylase digests the leftover starches into maltose. Trypsin converts peptones and proteoses into small peptides. Lipase acts on small droplets and converts them into triglycerides.The food reaches the small intestine where complete digestion of food takes place in the presence of an enzyme called succus entericus. The maltose converts into glucose, peptide emulsifies into amino acids and the triglycerides emulsifies into fatty acids and glycerol.?[OR(a)?In four chambered heart, left half is completely separated from right half by septa.This prevents oxygenated and deoxygenated blood from mixing. This allows a highly efficient supply of oxygenated blood to all parts of the body. This is useful in animals that have energy needs, such as birds and mammals.(b)24](d)?in set up A and (a) in set up B25]Sodium bicarbonate > Water > Fruit juice26]I27]A,?C,?D,?B28]A29]An antacid30]The final solution becomes light green31]MetalAl2(SO4)3CuSO4FeSO4(a) Alx??32]all the three cases33](ii)34](-4mA, +0.2V) and (2mA, 0.1V) respectively35]Student A will determine the equivalent resistance of series combination while student B will determine the equivalent resistance of parallel combination of the two resistors36]epidermal cells, stomata, guard cells each with one nucleus and many chloroplasts37]I?Cytoplasm?II?nucleusIII?stoma?IV?chloroplast38]39]Absorbs CO2?released by germinating seeds40]Thin layer of fleshy leaf of onion41]The glow of the bulbs B2?and B3?will remain the sameSAMPLE PAPER –IIsolutions:1]Gallium or Cesium (any one).2]Cerebellum3]Since ventricles have to pump blood into various organs, therefore, they have thicker muscular walls than the auricles.4]Commercial unit of energy is Kilowatt hour or KWh.5]Chemical reaction in which one reactant gets oxidized while the other gets reduced is called a redox reaction.Mg gets oxidized on burning in air.6](i) Fresh milk is acidic and gets spoiled easily. In presence of baking soda, milk becomes alkaline and can be stored for a longer time.(ii) When milk sets to curd, pH decreases. The alkali does not allow it to become more acidic easily. So it takes more time.7]Name of gland?SecretionSalivary gland?SalivaGastric gland?Gastric juiceLiver?BilePancreas?Pancreatic Juice(any two)8](a) When Iron nails are kept into a copper sulphate solution, Iron displaces copperfrom CuSO4?solution and blue colour of CuSO4?solution becomes light green.(b)?9](a) Ionic compounds are formed by the transfer of electrons from metal to non metal.(b)10](a) Respiration is an exothermic process since energy is released during theprocess.(b) Energy in the form of heat, light or electricity is required for decomposition Reactions hence these are endothermic.(c)The solution becomes colourless because of copper sulphate formed which is colourless.11](i) Test the three solutions with blue litmus paper, the one solution will change?blue litmus into red it is Acidic solution(ii) Test the remaining two solution with the red litmus (Changed in activity (i)) one solution will change it again to blue It is basic solution.?(iii)?Remaining third solutions is distilled water12]13]In series?(i)?R1?= 5+5 =10?(ii)?R2?= 6+4 = 10?In pararell(i)14](i) Glottis gets covered by a small cartilaginous flap of skin called epiglottis which prevents the entry of food particles into wind pipe while swallowing.(ii) The lung alveoli are richly supplied with blood capillaries for the exchange of gases. From the thin walls of alveoli, oxygen diffuses into blood and is supplied to the tissues while carbon dioxide is absorbed by blood from the tissues and is carried to the alveoli of lungs for exhalation.(iii) The walls of trachea is supported by C – shaped cartilage rings which does allow the trachea to collapse in the presence of less air in it.15]Hind brain has three parts:(i) Cerebellum: It is the regulating centre for swallowing, coughing, sneezing and vomiting and helps to maintain the balance of the body and coordinate the muscular activities.(ii) Pons: It takes part in the regulation of respiration.(iii) Medulla oblongata: It is responsible for the coordination and adjustment of movement and posture.16](a) Diagram of Neuron:Functions of Neuron:(i)?To carry information from receptors to brain and spinal cord.(ii)?To transfer respose from brain and spinal cord to effectors.17](a) Auxin.When light is coming from one side of the plant auxin diffuses towards shady sides.This concentration stimulates the cells to grow longer on the side of the shoot which is away from the light and shoot bends.18](i)?Magnetic field will increase(ii)?Magnetic field will decrease(iii) Magnetic field will increase19](i)?Wave energy be a viable proposition only when waves are very strong.?[1x3=3](ii)?A tidal power station at the mouth of a river blocks the flow of polluted water into the sea. It creates health and pollution hazards.(iii)?Efficient commercial exploitation is difficult or any other.20](a)(b) Functions of two chambers of human heart:Left Atrium – Receive oxygenated blood from pulmonary veinRight Atrium – Receive deoxygenated blood from vena cavaLeft Ventricle – Pumps oxygenated blood to all parts of bodyRight Ventricle – Pumps deoxygenated blood to lungs. (Any two)OR(a)?Diagram of stomata:(b) Functions of stomata:(a)?Exchange of gases(b)?TranspirationRaw materials for photosynthesis CO2, H2O21](a) The chemical name of washing soda is Sodium carbonate Decahydrate.The formula is Na2CO3.10H2OIt is obtained by heating baking Soda and then recrystallization.(b)?Distilled water is a pure form of water and is devoid of any ionic species. Therefore, it does not conduct electricity.?Rain water, being an impure form of water, contains many ionic species such as acids and therefore it conducts electricity.OR(a)(i)?Neutral- Solution D with pH 7 (ii) Strongly alkaline- Solution C with pH 11 (iii) Strongly acidic- Solution B with pH 1 (iv) Weakly acidic- Solution A with pH 4 (v) Weakly alkaline- Solution E with pH 9The pH can be arranged in the increasing order of the concentration of hydrogen ions as: 11 < 9 < 7 < 4 < 1(b)?The fizzing will occur strongly in test tube A, in which hydrochloric acid (HCl) is added.This is because HCl is a stronger acid than CH3COOH and therefore produces hydrogen gas at a faster speed due to which fizzing occurs.22](i)?Metal – sodium(ii)??(iii)Electrolysis of molten chloride (NaCl) is the process.i.e. we can write:ORDefinition: Homogeneous mixture of two or more metals or a metal and a non metal is called an alloy.Prepared:?(i)?By melting the primary metal.(ii)?By dissolving the other elements in a definite proportion and cooled to room temperature.23]A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder.The magnetic field is uniform inside the solenoidUsed to magnetise a piece of magnetic material.OR(a)(i)?Right hand Thumb rule(ii)?Fleming's Left hand rule(iii)?Fleming's Right hand rule(b)(a)?To avoid the risk of electric shocks(b)To save the electrical appliances from damage.24](a)(i)?Momentary deflection in the galvanometer to one side.(ii) Momentary deflection in the galvanometer now in opposite direction.(iii) No deflection in the galvanometer. Phenomenon involved is electromagnetic induction.(b) An energy source that can be replenished in a short period of time and state one use each.Eg. Solar Energy, Wind energy, Ocean energy etc. Any use.OR(a)Argon or Neon gas is filled in the electric bulbs.These are used since these are inactive or inert gases to prolong life of the filament.?(b)(i) Length of the conductor: proportional(ii) Area of cross section: inversely proportional(iii) Material of conductor25]26]II27]1A in Circuit I and 0A in Circuit II28]929]Parallel in circuit I and in series in circuit II30]A=Digestor,B=Gas outlet31]Safrainin32]Alcohol33]Alcohol is inflammable34]Germinating seeds35]To absorb CO2?released by germinating seeds36]Covered portion of any of the above37]Green38]Sodium bicarbonate > Water > Fruit juice39]A40]Light green41]NaOH42](i) and (ii)SAMPLE PAPER –IIISolutions:1]2]The receptors present in the specific regions of the tongue are called gustatory receptors.3]A large number solar cell combined in an arrangement.4](i) Human kidney performs the excretion by cleaning the blood of metabolic wastes.(ii) It performs the function of osmoregulation by maintaining normal levels of water and mineral ions in the body fluids.5]'Zn' being more reactive?displaces 'Cu' from CuSO4?solution CuSO4?solution becomes Colourless.(blue)?(colourless)6]The pH of milk decreases from '6' as it turns into curd.?That is curd is more acidic than milk.7]Resistance depends upon:(i)?Length of the conductor(ii)?Area of cross section(iii)?Material of conductorResistivity depends on:(i)?Material(ii)?TemperatureSI Unit of resistance is 'Ohm' or?8](i)?Each appliance have equal potential differenc(ii)?Each appliance have a separate switch to on/off(iii)?Each appliances can be operated on different current9](a)?Momentary deflection in the galvanometer to one side.(b)Momentary deflection in the galvanometer now in opposite direction.(c)No deflection in the galvanometer.(d)Phenomenon involved is electromagnetic induction.(e) Momentary deflection in the galvanometer now in opposite to the direction of the first case.(f) No deflection in the galvanometer.10](i)?Xylem – water and minerals in plants(ii)?Pulmonary Artery – Deoxygenated blood from heart to lungs.(iii)?Pulmonary Vein – Oxygenated blood from lungs to heart.Phloem – Synthesised food in plants11]1)Methane or CH42)?Hydrogen3)?Hydrogen sulphide4)?CO2Uses?Any two:. For the production of electricity ii. As a fuel to produce heat and light. iii. Biogas generation is an effective method of the disposal of bio wastes like, animal wastes and sewage.12](i) Ionic Compounds which are held together by?strong ionic bonds?so high?amount of energy is required to break these bonds.(ii)Ionic compounds are very hard solids due to strong force of attraction between positive and?negative?ions.(iii)Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal.13](a) Chemical reaction in which one reactant gets oxidized while the other get reduced is known as a redox reaction.When Magnesium ribbon burns in air, magnesium is oxidized and the white residue formed is of magnesium oxide.(b) Chemical equations must always be balanced to follow the law of conservation of mass, according to which "Mass can neither be created nor destroyed in a chemical reaction."14](i) This is an example of decomposition reaction and it is endothermic in nature.(ii) This is an example of combination reaction?and it is also a type of endothermic reaction.(iii) This is an example of displacement reaction?and it is exothermic reaction.15](i) The chemical name of 'Plaster of Paris' is 'Calcium sulphate Hemi hydrate'(ii) It is prepared on heating gypsum at 373 K(iii)16](i)(ii)?In series?R2?=7?+ 3?=10R3?=6?+ 4?= 10In ParallalOR17]The gastric glands in the stomach secrete:(i) HCl – It kills the bacteria ingested with food and makes the medium of food acidic so as to facilitate the action of the enzyme pepsin.(ii) Pepsin – It helps to digest proteins.(iii) Mucus – It protects the inner lining of the stomach from the action of HCl18]The functions of fore brain are:(i) It has sensory area where information is received from sense organs.(ii) It has motor area where impulses are sent to muscles or effector organs.(iii) It has centres for visual reception, touch, smell, temperature and muscular activities.19](a) Diagram of Neuron:Functions:(i)?To carry information from receptors to brain?and spinal cord.(ii)?To transfer respose from brain and spinal cord to effectors.20](a) The glands which does not have duct and secretes it's product directly into blood stream is called an endocrine gland.Two glands are: Thyroid and pancreas.Thyroid secretes thyroxin and pancreas secretes insulin.21](a)(i)?Test the three solutions with blue litmus paper, the?solution that changes l?blue litmus into red is Acidic solution.(ii)?Test the remaining two solution with the red litmus?one solution will change it again to blue –then that solution?is basic solution.(iii) Remaining third solutions is distilled water which being neutral does not cause any colour change of either the blue or red litmus paper.(b)?Plaster of Paris should be stored in a moisture-proof container because Plasterof Paris, a powdery mass absorbs water (moisture) to form a hard solid known as gypsum.OR(a)?Two important used of washing soda and baking soda are as follows:?Washing soda:(i) It is used in glass, soap, and paper industries.?(ii) It is used to remove permanent hardness of water.Baking soda:- (i) It is used as baking powder. Baking powder is a mixture of baking soda and a mild acid known as tartaric acid. When it is heated or mixed in water, it releases CO2?gas that makes bread or cake fluffy. (ii) It is used in soda-acid fire extinguishers.(b) Acids dissociate in the presence of water to give free hydrogen ions. It is the hydrogen ions that are responsible for the acidic behaviour.22](i)?Metal – sodium(ii)?(ii)?Electrolysis of molten chloride (NaCl)ORDefinition:?Homogeneous mixture of two or more metals or a metal and a non metalPrepared:(i)?Melting the primary metal.(ii)?Dissolving the other elements in a definite proportion and then cooling them?to room temperature?.23]A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder.The magnetic field is uniform inside the solenoidUsed to magnetise a piece of magnetic material.OR(a)?(i)?Right hand Thumb rule(ii)?Fleming's Left hand rule(iii)?Fleming's Right hand rule(b)?(a)?To avoid the risk of electric shocks?(b)?To save the electrical appliances from damage.24](a)(b) Functions of chambers of human heart:Left Atrium – Receive oxygenated blood from pulmonary veinRight Atrium – Receive deoxygenated blood from vena cavaLeft Ventricle – Pumps oxygenated blood to all parts of bodyRight Ventricle – Pumps deoxygenated blood to lungs. (Any two)OR(a) Diagram of Stomata:Functions(a)?Exchange of gases(b)?TranspirationRaw materials for photosynthesis are CO2, H2O25]Green26]Sodium bicarbonate > Water > Fruit juice27]A28]Hydrogen29]Red30]Calcium31]0.2532]0A in Circuit I and 1A in Circuit II33]934]335]Parallel in circuit I and in series in circuit II36]37]Glycerine38]Alcohol39](I)?Guard cell(II)?Nucleus(III)?Stoma(IV)?Chloroplast40]Germinating seeds41]To absorb CO2?released by germinating seeds42]Covered portion of any of the aboveSAMPLE PAPER –IVSolutions:1]Metal: Mercury: Non metal: Bromine2]The brain box called cranium protects the brain and has shock absorbing fluid in it which prevents it from shock and injuries.3](i)?Volmeter?(ii)?Ammeter4]It is a reaction in which there is an exchange of ions between the reactantsNa2SO4(aq) + BaCl2(aq)???BaSO4(s) +2NaCl(aq) or any other5]HCl and HNO3?produce H+?ions in aqueous solution. Hence, they show acidic character.Alcohol and Glucose do not produce H+?ions in aqueous solution, hence, they do not show acidic characters.6]Glucose that enters the nephron along with the filtrate after passing through the glomerulus, passes from the tubule of nephron where it is selectively reabsorbed and sent back to blood.7]8](a)Let Resistance of a wire = RWhen cut into 3 equal partsResistance of each part =?When connected in Parallel, net resistance Rp:(b)?Resistivity will remain same.?(c)?Current through each part will be triple the previous and total current in the circuit will be 9 times.9](a)?Strength of magnetic field (B) is inversely proportional to radius of the coil (r)(b)?Directly proportional to the Number of turns in the coil (N)?( c)?The magnetic field lines will be like:10]At the roots, cells in contact with the soil actively take up ions. It creates a difference in the concentration of these ions between roots of soil. To eliminate this difference, water moves in to the roots from the soil. Thus water of minerals are absorbed by the plants.11](i)?Buring of coal or Petroleum Products lead to air pollution(ii)?The oxides of C, N and S are released on buring fossil fuels as acidic oxides it leads to acidic rain and affect water soil.(iii)?CO2, a green house gas causes global warming (or any other relevant point)i. Source of electricity in artificial satellites ii. Used as source of electricity in radio and wireless transmissions, at TV relay stations, traffic lights and research centers.12](a) Oxidation: gain of oxygen by a substance?or any other exampleReduction: loss oxygen by a substance?or any example(b)?Sodium (Na) is oxidised to sodium oxide as it gains oxygen and oxygen gets reduced.13](a) The compounds formed by transfer of electrons from metal to non metal are called ionic compoundsIn ionic compounds, there are strong electrostatic forces of attraction between the oppositely charged ions. Due to this, movement of ions is not possible due to their rigid structure.In molten state, the electrostatic forces of attraction between the oppositively charged ions are overcome due to heat.(b)?Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.14]Exothermic: Reactions in which heat is released.Endothermic: Reactions in which heat is absorbed.?or any other15]When the pH of mouth of a person is lower than 5.5 tooth decay startsTooth enamel?made up of calcium phosphate is corroded.Measures:(i)?Clean the mouth after eating food(ii)?Use of toothpaste (generally basic in nature)16]The functions of fore brain are:(i) It has sensory area where information is received from sense organs.(ii) It has motor area where impulses are sent to muscles or effector organs.(iii) It has centres for visual reception, touch, smell, temperature and muscular activities.17]The following events occur during photosynthesis:(i) Absorption of light energy by chlorophyll.(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.(iii) Reduction of carbon dioxide to carbohydrates.18]GlandHarmoneFunctionThyroidThyroxinRegulates fat protein and carbohydrate metabolismsPancreaseInsulinRegular blood sugar levelAdrenal glandAdrenalinePrepage the body to face the emergency situation and blood pressure19]Auxin diffuses to the other part which is away from the support.?Part of the tendril in contact from the support does not grow rapidlyPart of the tendril away from the support grow rapidly and cause the tendril to grow around a support.20](a)?Bleaching Powder(b)?CaOCl2(c)?(d)?Bleaching powder is used:(i) as an oxidising agent in many chemical industries; and(ii) for disinfecting drinking water to make it free of germs.OR(a) The chemical equation for the reaction of Plaster of Paris and water can be represented as:(b) Calcium hydroxide [Ca(OH)2], on treatment with chlorine, yields bleachingpowder.(c) Washing soda (Na2CO3.10 H2O) is used for softening hard water.(d) When a solution of sodium hydrogencarbonate is heated, sodium carbonate and water are formed with the evolution of carbon dioxide gas.21]Corrosion:?Process of slowly eating up of metals due to action of atmospheric gasesMetal does not corrode???GoldWhich corrode???Iron or any otherPrevention:(i)?By painting(ii)?By greasing or oiling(iii)?Galvinization(iv)?Tin plating/ Chromium plating etc.?(any three)OR(i)?(ii)??[1](iii)?(iv)?(v)?22](b) Exchange of gases take place in the alveoliOR(a)It receive secretion from liver and pancreas in the form of juice and trypsinTrysin digest proteins.Lipase digest fatsBile juice makes basic medium and emulsifies fatsIntestinal Juice converts proteins to amino acids Carbohydrates to glucose and fats to fatty acids and glycerol.23](b)(i) Over loading is caused when too many short circuit appliances are connected to a singl socket(ii) When live wire and neutral wire come into direct contactOR(i) North Pole to South Pole(ii) Tesla(iii) Strong magnetic field(iv) 50 Hz(v) Heart and brain24](i)?Separately: Current?(ii)?Series R=R1+R2=44(iii)?In ParallelAdvantages of solar cooker:(any two)?[1/2x4=2](1)?Free of cost(2)?Does not cause any pollution(3)?Nutritive value of food is retainedDisadvantages:(i)?Can not used in night(ii)?Can not be used in cloudy day(iii)?Direction of sunlight is need and to be adjusted frequently or any otherOR(a)?Deflection increases(b)?Direction of deflection changes(c)?Deflection decreases.?[1](d)?Looking at a crossection lying in the plane of the paper.??At a distance d from the wire, the magnetic field direction is as shown and the magnitude is constant for all points shown.25]sodium bicarbonate > water > lemon juice26]HCl27]II and IV28]SetHCl+ZnHCl+Na2CO3NaOH+ZnNaOH+Na2CO3(d)???X29]R > P > Q30]Displacement reaction31]B32]A33]34]0.535]Ammeter and rheostat36]1?37]Covered portion of any of the above38]Entry of air bubbles39]40]Dark room for 03 days41]I cytoplasm II nucleus III stoma IV chloroplast42]SAMPLE PAPER –V1]Adrenaline controls the rate of respiration. Pons is the part of the brain which controls the rate of respiration.2]Acid present in pickles or curd will react with metals like copper and poisonous salts are produced.3]60 W bulb because??ie resistance is inversely proportional to the power.4]When aluminium powder is heated with manganese dioxide the following reaction takes place:When Mn powder is heated with aluminum dioxide no reaction takes place because Mn is less reactive than Al and hence there will be no?displacement reaction.5]Baking powder is added to make breads soft and fluffy.?Baking soda and an edible acid like tartaric acid are its main ingredients.Baking soda (Sodium hydrogen carbonate) is added to release CO2?gas when heated.Tartaric acid is added to avoid the bitter taste by reacting with the Na2CO3?which is?formed by the heating of NaHCO3.6](i) Kidney infection or injury to kidneys.(ii) Restricted blood flow to kidneys.7]The lining of canal has muscles that contract rhythmically in order to push the food forward.Peristaltic movement is necessary to move the food in a regulated manner along the digestive tube so that the food can be processed properly in each part.8]Solar cooker with concave mirror reflector is more efficient.Because concave mirror can focus the heat radiations to the material kept inside to increase the temperature.Concave mirror is used in headlight of vehicles or as shaving mirror.9]Ohm's law relates current and potential difference.According to this law:?V/I = constant = R10]Ammeter, A1?will show higher reading.Because, as wire A is thicker than B, A has lesser resistance. So higher current will be drawn by A from the battery and hence ammeter A1?will show higher reading.11]Observation a is correct.Because force experienced by a current carrying conductor in a magnetic field is proportional to the strength of the current. Resistance of a conductor is due to the obstruction to the flow of electrons due to the collisions with atoms and other electrons.12](i) The substance 'X' is calcium oxide. Its chemical formula is CaO.?(ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).(iii)?13]Main ore is cinnarbar, HgS.When it is heated in air, it is first converted into mercuric oxide (HgO). Mercuric oxide is then reduced to mercury on further heating.14](a)Water of crystallisation is the number of water molecules that combine chemically in definite molecular proportion, with the concerned salt in the crystalline state.(b)?Two correct examples are:Copper sulphate ,chemical formula = CuSO4.5H2OWashing soda, chemical name =?Na2CO3.10 H2O.15](a) we can show it by an experiment of displacement reaction in which Mg rod is dipped in ZnSO4?solution. Magnesium displaces zinc from zinc sulphate solution.(b)Cu is less reactive then hydrogen and thus place below hydrogen in the reactive series of metals, hence cannot displace hydrogen in dilute HCl.16](a)?Functions:(i) Cerebrum:It controls the conscious sensations.(ii) Mid brain: It controls the auditory impulses.17]Chemotropism – Movement of plant parts due to chemical stimulus is called chemotropism.Example?- Growth of pollen tube.Plant Hormones:(i) Auxin - It helps the cells to grow longer at shoot tips.(ii) Gibberellin – Growth of stem.18](i) Glycogen and starch – Both are carbohydrates and stored food products.(ii) Chlorophyll and haemoglobin – Both are pigments.(iii) Arteries and veins – Both are blood vessels.19]Involuntary actions are the actions which cannot be controlled by us if we want to do so. There is no external stimulus involved. The action takes place on its own like digestion, heart beat, etc.Reflex action is a kind of involuntary action controlled by and takes due to external stimulus. Its respond to the stimulus is quick. Example – sneezing, blinking of eyes, etc.20]Series:ORFor maximum resistance, resistors are to be connected in series.For maximum current, resistance has to be minimum and so resistors are to be connected in parallel.I series = V/R series?= 6V/9?= 0.67 AI parallel = V/R parallel?= 6V/2?= 3AParallel connection is preferred over series for house hold circuits.21](a) Chloralkali process is used to prepare sodium hydroxide using sodium chloride.When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium hydroxide. The process is called the chlor-alkali process because of the products formed– chlor for chlorine and alkali for sodium hydroxide.(b)?(i) 7?(ii) less than 7OR(a)(i) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because inalkaline condition, milk does not set as curd easily.(ii) Since this milk is slightly basic than usual milk, acids produced to set the curd areneutralised by the base. Therefore, it takes a longer time for the curd to set.(b)?A reaction in which an acid and base react with each other to give a salt and water istermed as neutralisation reaction. In this reaction, energy is evolved in the form of?heat.For example:(i) NaOH + HCl?NaCl + H2O(ii) During indigestion (caused due to the production of excess of hydrochloric acid in thestomach), we administer an antacid (generally milk of magnesia, Mg(OH)2?which isbasic in nature). The antacid neutralizes the excess of acids and thus gives relief fromindigestion. Mg(OH)2?+ 2 HCl?MgCl2?+ 2 H2O22](a)Amphoteric oxides are those oxides which show?both acids as well as bases to form salts and water.Ex: Aluminium metal reacts in this manner with acids and bases.SnO2?is also an example?of amphoteric oxides.(b)?Metals such as Sodium and Potassium are kept immersed is Kerosene becausethey are very reactive and have high affinity towards oxygen and will violently react with atmospheric oxygen on contact with air.(c)?Aluminium reacts readily with?steam?to give?aluminium oxide?and?hydrogen gas, the reaction does not always occur. This is due to a thin but strong layer of aluminium oxide being coated onto the metal, thus preventing it from the reaction. aluminium + steamaluminium oxide + hydrogen 2Al(s) + 3H2O(g)?Al2O3(s) + 3H2(g)?[1](d)?(i)?Bromine?(ii)?IodineOR(a)?Diamond and graphite?are the two allotropes of carbon.Diamond –??hardest substance??electrical insulatorGraphite –??comparatively soft, it is slippery over layers??good electrical conductor(b)?Aluminium articles have a longer life and attractive finish compared to many other metals because of the formation of a thin transparent protective film cover of Aluminium oxide on the surface of Al formed due to its spontaneous reaction with oxygen.(c)?(i) Ore : An?ore?is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element(s).(ii) Gangue: In mining,?gangue?is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit.(d) Electronic configuration of metal atom is significant to know about the kind of bond that the metal will be forming for example in the formation of calcium chloride, chlorine only needs one electron to complete its octet so two atoms of chlorine accept one electron each lost by calcium ion.23](a)(i)?Part in which starch digestion starts – Mouth(ii)?Part in which bile is stored – Gall Bladder(iii)?Part in which nutrients are absorbed – Small intestine(iv)?Part in which water is absorbed – Large intestine(b)?Kills bacteria in the stomach (1/2) provide acidic medium for the action of pepsin.(c)?(i) Controls the release of food from the stomach to small intestine.(ii) Controls the release of undigested waste from the rectum through the anus.OR(a)(b) Within the lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon – like structures which are called alveoli.The walls of the alveoli contain an extensive network of blood-vessels which provides surface where the exchange of gases can take place.24]Brief explanation of activity:Connect the circuit as shown in the figure below. Switch on the battery so that the current begins to flow. Sprinkle some fine iron filings around the current carrying wire. Tap the surface gently. The iron filings get arranged in concentric circles.When current is decreased, field gets decreaseWhen the current is reversed, field also gets reversedORA magnet is placed on a sheet of paper. A compass needle is placed near the North Pole. The position of its two ends is marked with the help of a sharp pencil. Now the compass is moved in such a way that its south end occupies position occupied by north end previously. Again the two ends are marked with sharp pencil. In this way, process goes on step by step till the south pole of the magnet is reached. Now all points are joined to get a smooth curve which represents a field line. In this way many field lines can be drawnRegion A has stronger magnetic fieldBecause the strength of the?field is proportional to the relative closeness of field lines.25]Less than 3.526]Blue to red in A and no change in B27]MetalAl2(SO4)3CuSO4FeSO4ZnSO4(a) AlX???28]Carbon dioxide29]sodium bicarbonate > water > lemon juice30]Hydrogen gas and iron chloride are produced31]Student II only32]Both (ii) and (iii)33]Correct reading for current I incorrect reading for potential difference V34]17.535]A1?= A336]1.37 ?37]To make the plant free of starch, it is:38]The part not covered turns blue39](ii), (iii), (iv), (i)40]441](i), (iii), (iv), (ii)42]A is KOH solution and B is water ................
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