Mark Scheme (Results) January 2012 - Edexcel

Mark Scheme (Results) January 2012

International GCSE Chemistry (4CH0) Paper 2C

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January 2012 Publications Code UG030257 All the material in this publication is copyright ? Pearson Education Ltd 2012

INTERNATIONAL GCSE CHEMISTRY 4CH0 2C ? JANUARY 2012

Question number 1 (a)

Expected Answer

relative mass

relative charge

Proton 1

Neutron 1

0

Electron -1

1 mark for each correct answer (b) (i) Protons AND electrons = 1

neutrons = 2

(ii) atoms of the same element

with different masses Ignore references to electrons

Accept

Reject

+1

- 1 / one

Zero minus one /negative

one two

atoms with same atomic number / number of protons / proton number

molecules / compounds for first mark only

with different mass numbers / different numbers of neutrons / different neutron numbers

different relative atomic masses for second mark only

Marks 4

1 1 1 1

Question number

Expected Answer

1 (c)

((79 x 50.7) + (81 x 49.3))/100

OR

(79 x 0.50.7) + (81 x 0.493)

Accept

= 79.99 Allow 1 mark for a single transcription error (e.g. 43.9 instead of 49.3) Ignore units such as grams

Correct answer on its own scores 2

Reject

Marks

1 1

Total 10

Question number 2 (a) (i)

(ii) (iii) (iv) (b) (i) (ii)

Answer

B A E C Atomic number Electrons in the outer shell

Accept

Reject

Marks

1 1 1 1 1 1 Total 6

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