DP Chemistry (last assessment 2024)

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Question 19M.1.hl.TZ1.24

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.1.hl.TZ1.24
Level hl Paper 1 Time zone TZ1
Command term Question number 24 Adapted from N/A
24.
[Maximum mark: 1]
19M.1.hl.TZ1.24

Which solution is basic at 25 °C?

Kw = 1.0 × 10−14

A. [H+] = 1.0 × 10−3 mol dm−3

B. [OH−] = 1.0 × 10−13 mol dm−3

C. solution of pH = 4.00

D. [H3O+] = 1.0 × 10−13 mol dm−3

[1]

Markscheme

D

Examiners report

This had the highest discriminatory index on the exam. Most of the incorrect answers indicated that a basic solution would have [OH- ] = 1.0 x 10-13 mol dm-3 rather than [H3O+ ] = 1.0 x 10-13 mol dm-3 .

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