I. Treatment of cancer II. Detection of leakages in water mains III. Detection of the ages of ancient tools IV. Preparation of drugs Which combination of the above refers to the uses of radioactive isotopes?

• A. I and III
• B. I and II
• C. I, II and III
• D. I, II, III and IV

The density of a certain gas is 1.98gdm-3 at s.t.p. What is the molecular mas of the gas?

• A. 44.0 g
• B. 54.0 g
• C. 26.0 g
• D. 31.0 g

A concentrated solution containing H⁺, Cu²⁺, OH^- and Cl^- was electrolyzed using platinum electrodes. The ion that will be discharged at the cathode is

• A. Cu²⁺
• B. Cl^-
• C. H⁺
• D. OH^-

When pure aluminium metal is heated to red hot in the presence of nitrogen gas, the compound formed is

• A. Al₂N
• B. Al₂N₂
• C. AlN
• D. Al₂N₃

Which of the following ions require the largest quantity of electricity for discharge at an electrode?

• A. 4.0 moles of Cl^-
• B. 3.0 moles of Na⁺
• C. 2.5 moles of Cu²⁺
• D. 2.0 moles of Al³⁺

The gas that can be dried using concentrated tetraoxosulphate (VI) acid is

• A. hydrogen bromide
• B. Sulphur (IV) oxide
• C. hydrogen sulphide
• D. ammonia

Sugar is separated from its impurities by

• A. precipitation
• B. crystallization
• C. distillation
• D. evaporation

How many hydrogen atoms does a single ring cycloalkane have less than the corresponding open-chain alkane?

• A. Two
• B. Three
• C. Four
• D. One

A dense white fume is formed when ammonia gas reacts with

• A. O₂(g)
• B. H₂(g)
• C. Cl₂(g)
• D. HCl(g)

The gas that is the most dangerous pollutant to human is

• A. sulphur (IV) oxide
• B. carbon (IV) oxide
• C. nitrogen (II) oxide
• D. hydrogen sulphide