DP Chemistry (last assessment 2024)

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Question 19M.1.sl.TZ2.24

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.1.sl.TZ2.24
Level sl Paper 1 Time zone TZ2
Command term Question number 24 Adapted from N/A
24.
[Maximum mark: 1]
19M.1.sl.TZ2.24

Which compound has the lowest boiling point?

A. CH3CH2CH2CH2CH2CH3

B. CH3CH2CH2CH2CH3

C. CH3CH(CH3)CH2CH3

D. CH3C(CH3)2CH3

[1]

Markscheme

D

Examiners report

Surprisingly, this was one of the challenging questions on the paper. Only 57 % of the candidates chose dimethylpropane as the compound having the lowest boiling point. The most commonly chosen distractor was pentane (B) which did not take into account the effect of branching on the strength of London dispersion forces.

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