2015 A Level H2 Chemistry Paper 1, 2, 3

last SG · 2015-11-06T20:43:51+00:00

History students!! Do check out my site for notes that will guarantee you an A in H2 History :) pass on the message to all who are struggling with this subje...

Lololgirl SG

Kk thanks for clarifying once again !

Weihaw08 SG

Hi! I have a question regarding the ideal gas question in paper 3.

Is the actual volume of the HCl gas supposed to be higher or lower than the predicted volume based on pV = nRT? Based on calculations, it seems that the actual volume is lower than the predicted volume. However, I had read that the volume of a real gas should be greater than an ideal gas at high pressures. Mind clarifying any misconceptions/errors I have made? Thanks in advance!

UltimaOnline SG

Hi! I have a question regarding the ideal gas question in paper 3.

Lower. As real gases have significant van der Waals attractions between the molecules that cause them to be attracted to each other, hence smaller volume. Ideal gases have no van der Waals attractions between molecules.

UltimaOnline SG

Ladies & Gentlemen, the ‘A’ grade boundary for 2015 A Levels H2 Chemistry has just shot up to 75%.

Vitalitylx SG

no +- 1% between 75?xD

UltimaOnline SG

2015 H2 Chemistry Paper 1 MCQ Answers by BedokFunland JC

(If you disagree with any of the answers, post your reasons why.)

1. B
2. D (for hydrocarbons, if "p orbitals" refer strictly to unhybridized p orbitals only) or B (generally, and for hydrocarbons too if "p orbitals" includes hybridized orbitals)
3. C
4. C
5. B
6. D
7. B
8. C
9. A
10. B
11. D
12. C
13. D
14. B
15. D
16. D
17. A
18. C
19. B
20. A
21. B
22. D
23. B
24. A
25. D
26. D
27. D
28. C
29. B
30. A
31. D
32. A
33. C
34. A
35. B
36. A
37. C
38. C
39. A
40. B

DUbPie SG

UltimaOnline SG

Q35. Since backward reaction favoured, the magnitude of increase in k-backward will outweight the magnitude of increase in k-forward.

Q40. The internal plane of symmetry is for 3, not 1.

DUbPie SG

Vitalitylx SG

shouldnt 33 be A since ideal gas particles has no mass and thus no volume?

UltimaOnline SG

( ͡° ͜ʖ ͡°)

UltimaOnline SG

shouldnt 33 be A since ideal gas particles has no mass and thus no volume?

Ideal gas only assumes no volume (for individual particles, not gas volume), no assumptions made about mass.

DUbPie SG

UltimaOnline SG

thanks for the reply really appreciate it so is 37/40 a good score?

No prob :)

You need 75% overall score to get A grade this year. 37/40 = 92.5%, but bear in mind P1 is only 20% weightage, so as long as your P2 + P3 + SPA ideally all > 75% (or at minimum your overall combined scored > 75%), you can go enjoy your holidays and celebrate liao! ;)

nelexus SG

For Q2,

why can a sigma bond be formed by either an s or p orbital? does an sp3/ sp2 hybridised orbital also imply that theres a p orbital? because my nterpretation of this question is that p orbitals solely refers to unhybridised p orbitals?

Lamejaneinschool SG

Hi, thank you for the suggested answer,

May I know why is qn 1 b not c?

Qn 4, why cannot d? Metallic bonding depends on both delcalised electrons and charge.

39, if alkaline kmno4, wouldn't it not oxidise?

UltimaOnline SG

For Q2,

2. D (for hydrocarbons, if "p orbitals" refer strictly to unhybridized p orbitals only) or B (generally, and for hydrocarbons too if "p orbitals" includes hybridized orbitals)

Cambridge's fault for being ambiguous. Singapore JC school teachers and other private tutors are divided on what's the best answer.

UltimaOnline SG

Hi, thank you for the suggested answer,

May I know why is qn 1 b not c?

Qn 4, why cannot d? Metallic bonding depends on both delcalised electrons and charge.

39, if alkaline kmno4, wouldn't it not oxidise?

Q1. C is wrong because you need to fill the 2s orbital before you fill the 2p orbital.

Q4. Magnitude of cationic charge is the most important factor. Even considering no. of delocalized electrons, Ca2+ still as more delocalized electrons available for metallic bonding than Na+ (inner shell electrons are irrelevant).

Q39. It's not about oxidation (since heating under reflux wasn't specified), it's about alkaline solution deprotonates phenol.

nelexus SG

Indeed this is a tricky question, and many students struggled with this. Because in the H2 syllabus, every sigma bond is formed by the head-on or end-on overlap of either s orbitals or hybridized (sp, sp2, sp3) orbitals. But going beyond the H2 syllabus, sigma bonds can indeed be formed by the head-on or end-on overlap of p orbitals as well. Chemistry is chemistry (regardless of in or out of syllabus), so the correct answer to this question is still "sigma bonds can be formed by either s or p orbitals".

https://en.wikipedia.org/wiki/Sigma_bond

https://sites.google.com/site/ed350201003/Task

In this case the context is hydrocarbon..so im guess now the s orbital of hydrogen overlap with (unhybridised) p orbital of C to form a C-H bond?

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