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IGCSE Chemistry Extended3.3 The mole and the Avogadro constantTopic Practice

3.3 The mole and the Avogadro constant

CAIE IGCSE Chemistry Extended 3.3 The mole and the Avogadro constant question practice helps you revise this syllabus point with the course map in view. Use this page to focus on one topic, check the style of questions available, and connect each attempt back to the knowledge area it is testing.

EduNinja keeps Chemistry practice aligned to CAIE at Extended level, so you can move from topic review into exam-style question bank work without losing the syllabus structure. Start with a small set, mark the weak steps, then return to nearby topic links when a definition, graph, calculation, or explanation needs repair.

Question 1(b)(i)

[Maximum number: 2]

Iron ore contains iron(III) oxide, Fe2O3\mathrm{Fe}_{2} \mathrm{O}_{3}. A blast furnace is used to extract iron from Fe2O3\mathrm{Fe}_{2} \mathrm{O}_{3}.
Equations for some of the reactions in the blast furnace are shown.

equation 1C+O2→CO21 \mathrm{C}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}

equation 2CaCO3→CaO+CO22 \mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}+\mathrm{CO}_{2}

equation 3CaO+SiO2→CaSiO33 \quad \mathrm{CaO}+\mathrm{SiO}_{2} \rightarrow \mathrm{CaSiO}_{3}

Iron(III) oxide, Fe2O3\mathrm{Fe}_{2} \mathrm{O}_{3}, in iron ore is converted to iron when it reacts with carbon monoxide, CO , in the blast furnace.

Calculate the percentage by mass of iron in iron(III) oxide, Fe2O3\mathrm{Fe}_{2} \mathrm{O}_{3}.

percentage=...............................%[2]percentage = ...............................\% [2]

Question 1

[Maximum number: 2]

This question is about elements X, Y and Z.

Question 1(b)(iii)

(a)

What is the name of the amount of any substance that contains 6.02×10236.02 \times 10^{23} particles?

[ 1 ]

Question 1(b)(iv)

(b)

The constant 6.02×10236.02 \times 10^{23} has a name.

What is the name of this constant?

[ 1 ]

Question 2(a)

[Maximum number: 3]

Period 3 contains the elements sodium to argon. This question asks about the chemistry of each of the Period 3 elements or their compounds.

Sodium nitrate is a white crystalline solid. When heated it melts and the following reaction occurs.

2NaNO3(I)→2NaNO2(I)+O2( g)2 \mathrm{NaNO}_{3}(\mathrm{I}) \rightarrow 2 \mathrm{NaNO}_{2}(\mathrm{I})+\mathrm{O}_{2}(\mathrm{~g})

A 3.40 g sample of sodium nitrate is heated.
Calculate the
- number of moles of NaNO3\mathrm{NaNO}_{3} used, mol
- number of moles of O2\mathrm{O}_{2} formed, mol
- volume of O2\mathrm{O}_{2} formed, in dm3\mathrm{dm}^{3} (measured at r.t.p.). dm3\mathrm{dm}^{3}

Question 7

[Maximum number: 1]

Which gas sample contains the smallest number of molecules?

A

4 g of helium

B

16 g of oxygen

C

28 g of carbon monoxide

D

28 g of nitrogen

Question 7

[Maximum number: 1]

The concentration of a hydrochloric acid solution is 0.5 mol/dm30.5 \mathrm{~mol} / \mathrm{dm}^{3}.
How many moles of hydrochloric acid are present in 25 cm325 \mathrm{~cm}^{3} of this solution?

A

0.0125

B

0.0200

C

12.5

D

20.0

Question 7

[Maximum number: 1]

Which gas sample contains the most molecules?

A

24dm324 \mathrm{dm}^{3} of carbon dioxide, CO2\mathrm{CO}_{2}

B

4 g of hydrogen, H2\mathrm{H}_{2}

C

36dm336 \mathrm{dm}^{3} of hydrogen chloride, HCl

D

14 g of nitrogen, N2\mathrm{N}_{2}

Question 7

[Maximum number: 1]

Which gas sample has the greatest mass?

A

5.0 moles of Cl2\mathrm{Cl}_{2}

B

10.0 moles of O2\mathrm{O}_{2}

C

15.0 moles of N2\mathrm{N}_{2}

D

20.0 moles of H2\mathrm{H}_{2}

Question 7

[Maximum number: 1]

The equation for the reaction of iron(III) oxide with carbon monoxide is shown.

Fe2O3+3CO→2Fe+3CO2\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}_{2}

What is the percentage yield of iron when 16.8 g of carbon monoxide reacts completely with iron(III) oxide to form 8.96 g of iron?

A

26.7%

B

40.0\%

C

53.3\%

D

80.0\%

Question 7

[Maximum number: 1]

Which sample contains the largest number of molecules?

A

16 g of methane, CH4( g)\mathrm{CH}_{4}(\mathrm{~g})

B

16 g of oxygen, O2( g)\mathrm{O}_{2}(\mathrm{~g})

C

16 g of phosphorus, P4( s)\mathrm{P}_{4}(\mathrm{~s})

D

16dm316 \mathrm{dm}^{3} of methane at r.t.p., CH4( g)\mathrm{CH}_{4}(\mathrm{~g})

Question 8

[Maximum number: 1]

A tablet contains 0.080 g of ascorbic acid ( Mr=176M_{\mathrm{r}}=176 ).
What is the concentration of ascorbic acid when one tablet is dissolved in 200 cm3200 \mathrm{~cm}^{3} of water?

A

9.1×10−5 mol/dm39.1 \times 10^{-5} \mathrm{~mol} / \mathrm{dm}^{3}

B

4.5×10−4 mol/dm34.5 \times 10^{-4} \mathrm{~mol} / \mathrm{dm}^{3}

C

9.1×10−2 mol/dm39.1 \times 10^{-2} \mathrm{~mol} / \mathrm{dm}^{3}

D

2.3×10−3 mol/dm32.3 \times 10^{-3} \mathrm{~mol} / \mathrm{dm}^{3}

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