Oxford AQA IGCSE · Chemistry (9202)

The mole concept: Practice Questions

4 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on The mole concept.

9 questions28 marksFree, no account

Question 1

1 mark

Calculate the number of moles in \( 22\text{ g} \) of carbon dioxide, \( \text{CO}_2 \).

(Relative atomic masses: \( \text{C} = 12; \text{O} = 16 \))

Question 2

1 mark

Calculate the total number of ions present in \( 0.25 \) moles of magnesium chloride, \( \text{MgCl}_2 \).

(Avogadro\u2019s constant = \( 6.02 \times 10^{23} \) per mole)

Question 3

1 mark

Methane, \( CH_4 \), is a common hydrocarbon fuel. Calculate the number of total atoms present in \( 0.5 \) moles of methane gas.
(Avogadro’s constant = \( 6.02 \times 10^{23} \) per mole)

Question 4

1 mark

A sample of hydrated copper(II) sulfate, \( \text{CuSO}_4 \cdot x\text{H}_2\text{O} \), has a relative formula mass (\( M_r \)) of \( 250 \).

Calculate the value of \( x \) in the formula.

(\( A_r: \text{Cu} = 64; \text{S} = 32; \text{O} = 16; \text{H} = 1 \))

Question 5

3 marks

Calculate the number of moles in \(20\text{ g}\) of calcium carbonate, \(\text{CaCO}_3\).
(Relative atomic masses: \(\text{Ca} = 40\), \(\text{C} = 12\), \(\text{O} = 16\))

Write your answer out first, then check it against the worked solution.

Question 6

6 marks

An oxide of nitrogen contains \( 30.43\% \) nitrogen by mass. If the relative formula mass of the compound is \( 92 \), determine its molecular formula.
(\( A_r: \text{N} = 14, \text{O} = 16 \))

Write your answer out first, then check it against the worked solution.

Question 7

3 marks

Calculate the mass of magnesium oxide produced when \( 0.25 \) moles of magnesium react completely with oxygen.
(\( A_r: \text{Mg} = 24, \text{O} = 16 \))

Write your answer out first, then check it against the worked solution.

Question 8

5 marks

A sample of methane gas, \( \text{CH}_4 \), occupies a volume of 7.2 dm³ at room temperature and pressure (rtp).

(a) Calculate the number of moles of methane in the sample.
(b) Calculate the mass, in grams, of this sample of methane.
(c) Calculate the number of molecules of methane present in this sample.

(Assume the molar gas volume at rtp is \( 24\text{ dm}^3 \text{/mol} \). Relative atomic masses: \( \text{C} = 12, \text{H} = 1 \). Avogadro’s constant = \( 6.02 \times 10^{23} \text{ per mole} \).)

Write your answer out first, then check it against the worked solution.

Question 9

7 marks

A sample of a gaseous hydrocarbon is found to contain 85.7% carbon and 14.3% hydrogen by mass.
(a) Calculate the empirical formula of the hydrocarbon.
(b) At room temperature and pressure (RTP), 0.42 g of this gas occupies a volume of 240 cm³. Calculate the relative molecular mass (\( M_r \)) and determine the molecular formula.

(Relative atomic masses: \( C = 12, H = 1 \); Molar gas volume at RTP = \( 24 \text{ dm}^3 \text{/mol} \))

Write your answer out first, then check it against the worked solution.

* The content provided by thinka is generated by AI and may not always be accurate or up-to-date. Please use it as a supplementary resource and verify with official materials.

You've seen the model answer. Now get yours marked.

This page can show you how a good answer looks. It cannot tell you what your answer was missing. thinka marks your written work against the real mark scheme in about 15 seconds.

Get My Answers Marked Back to the notes

Want more questions like these? Get a fresh set on this topic, marked as you go.