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CAIE IGCSE Chemistry 3.2 Relative masses of atoms & molecules Question Bank

Practise relative atomic and molecular mass definitions and calculations using formulae, equations and reacting mass data.

Syllabus
2026–2028
Course
Chemistry 0620

Exam points

  • use the carbon-12 scale to interpret definitions of relative atomic mass and relative molecular mass
  • calculate Mr or Ar from formulae and relative formula masses, including unknown elements
  • apply balanced equations to reacting-mass problems involving carbonates, oxides and gases

Covered syllabus points

3.2.1—Relative atomic mass, Ar, as the3.2.2—Relative molecular mass, Mr, as the3.2.3—Reacting masses in simple proportions

3.2 Relative masses of atoms and molecules question 1

[Maximum number: 1]

This question is about elements X, Y and Z.

Identify the atom against which the relative masses of all other atoms are compared.

3.2 Relative masses of atoms and molecules question 2

[Maximum number: 1]

What is the relative molecular mass, MrM_{\mathrm{r}}, of sulfur dioxide?

A

24

B

32

C

48

D

64

3.2 Relative masses of atoms and molecules question 3

[Maximum number: 1]

The equation for the reaction between hydrogen sulfide, H2 S\mathrm{H}_{2} \mathrm{~S}, and oxygen is shown.

2H2 S+3O2→2SO2+2H2O2 \mathrm{H}_{2} \mathrm{~S}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{O}

Which mass of oxygen is required to react with 5.1 g of hydrogen sulfide?

A

2.4 g2.4 \mathrm{~g}

B

4.8 g4.8 \mathrm{~g}

C

7.2 g7.2 \mathrm{~g}

D

14.4 g14.4 \mathrm{~g}

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