DP Chemistry (first assessment 2025)

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Question 21M.1A.SL.TZ2.3

Date	May 2021	Marks available	[Maximum mark: 1]	Reference code	21M.1A.SL.TZ2.3
Level	SL	Paper	1A	Time zone	TZ2
Command term	Determine	Question number	3	Adapted from	N/A

3.

[Maximum mark: 1]

21M.1A.SL.TZ2.3

Which molecule has the same empirical formula as molecular formula?

A. CH₃COOH

B. C₂H₅OH

C. C₂H₄

D. C₄H₁₀

[1]

Markscheme

B

Syllabus sections

Structure 1. Models of the particulate nature of matter » Structure 1.4—Counting particles by mass: The mole » Structure 1.4.4—The empirical formula of a compound gives the simplest ratio of atoms of each element present in that compound. The molecular formula gives the actual number of atoms of each element present in a molecule. Interconvert the percentage composition by mass and the empirical formula. Determine the molecular formula of a compound from its empirical formula and molar mass.