DP Chemistry (first assessment 2025)

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Question 20N.1A.HL.TZ0.27

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.1A.HL.TZ0.27
Level	HL	Paper	1A	Time zone	TZ0
Command term	Solve	Question number	27	Adapted from	N/A

27.

[Maximum mark: 1]

20N.1A.HL.TZ0.27

What is the pH of an ammonia solution that has $[{OH}^{-}] = 1 \times 10^{- 4} mol {dm}^{- 3}$ ?

A. $4.0$

B. $8.0$

C. $10.0$

D. $12.0$

[1]

Markscheme

C

Examiners report

More than 86% of candidates could find a pH from a given hydroxide concentration.

Syllabus sections

Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.9—The pOH scale describes the [OH–] of a solution. pOH = –log10[OH–]; [OH–] = 10–pOH. Interconvert [H+], [OH–], pH and pOH values.