DP Chemistry (first assessment 2025)

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Question 21M.1A.SL.TZ1.26

Date	May 2021	Marks available	[Maximum mark: 1]	Reference code	21M.1A.SL.TZ1.26
Level	SL	Paper	1A	Time zone	TZ1
Command term	State	Question number	26	Adapted from	N/A

26.

[Maximum mark: 1]

21M.1A.SL.TZ1.26

What is formed in a propagation step of the substitution reaction between bromine and ethane?

A. CH₃CH₂•

B. CH₃CH₂CH₂CH₃

C. H•

D. Br⁻

[1]

Markscheme

A

Syllabus sections

Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.3—Electron sharing reactions » Reactivity 3.3.3—Radicals take part in substitution reactions with alkanes, producing a mixture of products. Explain, using equations, the propagation and termination steps in the reactions between alkanes and halogens.