DP Chemistry (last assessment 2024)

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Question 22N.1.sl.TZ0.10

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Date November 2022 Marks available [Maximum mark: 1] Reference code 22N.1.sl.TZ0.10
Level sl Paper 1 Time zone TZ0
Command term Predict Question number 10 Adapted from N/A
10.
[Maximum mark: 1]
22N.1.sl.TZ0.10

Which molecule is polar?


A.  BeH2

B.  AlH3

C.  PH3

D.  SiH4

[1]

Markscheme

C

Examiners report

A well-answered question - 61% of the candidates selected PH3 as the polar molecule as the dipoles in the other symmetrical molecules would cancel out due to the molecular geometry. The question also discriminated well between high-scoring and low-scoring candidates. Some teachers were unhappy about the question as the electronegativities of P and H in the data booklet (which the students did not have access to in this paper) are identical. Apologies for this choice - a better example should have been used.

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