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Jun 15 MS.pdf


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MARK SCHEME – A-LEVEL CHEMISTRY – CHEM1 – JUNE 2015

Question
2(a)

Marking Guidance
5s2 4d10 5p4

/

Mark

4d10 5s2 5p4

1

Comments
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p4
or 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p4
Allow any order but must finish with 5p4

2(b)(i)

(124 × 2 ) + (126 × 4) + (128 × 7) + (130 × 6)

1

M1 for top line

1

M2 for correct denominator

127.8

1

127.8 with no working shown scores 3 marks

Or

Or

(124 x 10.5) + (126 x 21.1) + (128 x 36.8) + (130 x 31.6)

1

19

or 2428
19

100

2(b)(ii)

2(c)

1

127.8

1

Other isotopes present/some isotopes absent /different abundances of
isotopes

1

Te+ + e(–)  Te

1

Mark for 100 dependent on top line correct

Ignore state symbols
Allow Te2+ + 2e(–)  Te

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