MCQ Questions

Question No. 1

Give one word for each of the following descriptions.

Answer :

a) A solution of known concentration.

b) The SI unit for the amount of substance.

c) The mass of one mole of a compound.

d) Water contained around ions of certain salts.

e) The amount of solute present in a given volume of solvent.

f) Volume of one mole of gas.

Question No. 2

Oxygen gas and hydrogen gas react to form water.

Answer :

a) Write a balanced equation for the reaction.

b) Calculate the volume of water that is formed, if 30 cm³ of oxygen reacts with an excess of hydrogen gas at STP.

c) Calculate how many moles of oxygen gas there are in 30 cm³ of oxygen gas at STP.

d) Calculate the mass of oxygen that is used in the reaction at STP.

Question No. 3

Determine the molal concentration of:

Answer :

a) 3 moles of potassium chloride (KCl) dissolved in 500 ml of water

b) 12 g of barium hydroxide (Ba(OH)₂) dissolved in 2 dm³ of water

c) 6.0 moles of hydrogen bromide (HBr) dissolved in 0.200 kg of water

Question No. 4

You want to prepare a standard solution of LiCl with a molar concentration of 2 mol·dm–³. The volume of the volumetric flask is 250 ml.

Answer :

a) Convert 250 ml to dm³.

b) What is meant by the term “standard solution”?

c) How many grams of crystals do you need to make this standard solution?

Question No. 5

The density of various substances are listed in the table below.

Answer :

a) Name all the substances that will float on water.

b) Name all the substances that will sink in water.

c) When ethanol and methanol are mixed, which substance will float on top?

d) Calculate the relative density of ice, if the density of water is 1 000 kg·m–³.

Question No. 6

Calculate the molar mass of the following substances:

Answer :

a) H₂SO₄

b) Ammonia gas (NH₃)

c) KMnO₄

d) Iron(III) chloride (FeCl₃)

e) Mg(OH)₂

Question No. 7

Calcium reacts with hydrochloric acid to form calcium chloride and hydrogen gas. How many grams of calcium chloride are formed, when 15 g of calcium metal reacts with hydrochloric acid?

Answer :

Question No. 8

How many grams of CaCO₃ are needed to react with 15.2 g of HCl, according to the following equation? CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

Answer :

Question No. 9

What volume of oxygen will react with carbon monoxide, to produce 20 dm³ of carbon dioxide at STP?

Answer :

Question No. 10

Calcium carbonate decomposes to produce calcium oxide and carbon dioxide. How many grams of calcium carbonate decompose to produce 11.2 dm³ of carbon dioxide at STP?

Answer :

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