MCQ Practice

Read question carefully.

• A

• B

• C

• D

Answer explanation

A gas syringe is used in the expt set-up so a gas is produced in the reaction. Option C is wrong as water produced is a liquid, not gas.

Read question carefully.

• A

• B

• C

• D

Answer explanation

Mr of magnesium chloride = 24 + 2 x 35.5

= 95

No of moles of magnesium chloride = 3.8 ÷ 95

= 0.04 mol

From the eqn, 1 mol MgCl₂ : 2 mol AgCl

No of moles of silver chloride = 0.04 x 2

= 0.08 mol

Mr of silver chloride = 108 + 35.5

= 143.5

Mass of silver chloride = 0.08 x 143.5

= 11.48 g

Read question carefully.

• A

• B

• C

• D

Answer explanation

MnO₄ ^- is reduced to Mn²⁺ as the oxidation state of Mn decreases from +7 in MnO₄^- to +2 in Mn²⁺.

The reducing agent is SO₃^2- .

There is no change in oxidation state of hydrogen in H⁺ and H₂O. It remains at +1.

Read question carefully.

• A

• B

• C

• D

Answer explanation

The diagram shows 5 protons so the element is boron.

From the diagram, there are 7 neutrons so the mass number is (7+5 = 12).

Read question carefully.

• A

• B

• C

• D

Answer explanation

From the qn, the heated copper reacted with oxygen to form copper(II) oxide.

% of oxygen in air = 21%

vol of oxygen in air sample = 21∕100 × 80

= 16.8 cm³

vol of air remaining = 80 - 16.8

= 63.2 cm³

Read question carefully.

• A

• B

• C

• D

Answer explanation

Option B is used to obtain insoluble solid from mixture.

When aqueous solution of potassium chloride is evaporated, crystals are left behind.

Read question carefully.

• A

• B

• C

• D

Answer explanation

Line Y shows steeper gradient and more vol of oxygen produced.

This means faster reaction and more limiting reactant. As hydrogen peroxide is the only reactant, it is the limiting reagent.

From the qn, manganese oxide is a catalyst which increase the speed of reaction hence if it is added, the gradient would become steeper.

Read question carefully.

• A

• B

• C

• D

Answer explanation

From the qn, iron(III) chloride reacts with potassium iodide to form a brown solution. This means it oxidised potassium iodide to form iodine, a brown solution. Hence it is a OA.

From the qn, iron(II) chloride reacts with acidified potassium manganate(VII) to form a pale yellow solution which is iron(III) chloride. Hence iron(II) chloride is oxidised and is a RA.

Read question carefully.

• A

• B

• C

• D

Answer explanation

Melting point decreases down Group I.

Hence, R is above T in Group I.

Read question carefully.

• A

• B

• C

• D

Answer explanation

This is a type of displacement reaction.

Count the number of reactions that each metal undergoes.

The more reactive a metal, the more reactions it undergoes.