The addition of water to calcium oxide leads to?

A. a physical change

B. a chemical change

C. the formation of a mixture

D. an endothermic change

A mixture of iron and sulphur can be separated by dissolving the mixture in?

A. steam

B. dilute hydrochloric acid

C. dilute sodium hydroxide

D. benzene

A given amount of gas occupies 10.0 dm³ at atm, and 273°C. The number of moles of the gas present is?
(Molar volume of a gas at s.t.p. = 22.4 dm³)

A. 0.89 mol

B. 1.90 mol

C. 3.80 mol

D. 5.70 mol

8.0 g of an element X react with an excess of copper (ll) tetraoxosulphate (lV) solution to deposit 21.3 g of copper. The correct equation for the reaction is?

(Cu = 64).

A. X_(s) + CuSO_4(aq) → Cu_(s) + XSO_4(aq)

B. X_(s) + 2CuSO_4(aq) → 2Cu_(s) + X(SO₄)_2(aq)

C. 2X_(s) + CuSO_4(aq) → Cu_(s) + X₂SO_4(aq)

D. 2X_(s) + 3CuSO_4(aq) → 3Cu_(s) + X₂(SO₄)_3(aq)

C₃H_8(g) + 50_2(g) → 4H₂O + 3CO_2(g). Form the equation above the volume of oxygen at s.t.p. required to burn 50cm³ of propane is?

A. 250 cm³

B. 150 cm³

C. 100 cm ³

D. 50 cm³

30cm³ of hydrogen was collected over water at 27°C and 780 mm Hg. If the vapour pressure of water at the temperature of the experiment was 10 mm Hg, calculate the volume of the gas at 760 mm Hg and 7°C?

A. 40.0 cm³

B. 35.7 cm³

C. 28.4 cm³

D. 25.2 cm³

If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso₂ and Rch₄ will be in the ratio?

(S = 32, O = 16, C = 12, H = 1)

A. 4:1

B. 2:1

C. 1:2

D. 1:4

A solid begins to melt when?

A. constituent particles acquires a greater kinetic energy

B. energy of vibration of particles of the solid is less than the intermolecular forces

C. constituent particles acquires energy above the average kinetic energy

D. energy of vibration of particles of the solid equals the intermolecular forces