1. The non-metal which is liquid at room temperature is:

a) Mercury

b) Bromine

c) Carbon

d) Helium

Answer: (b) Bromine

Explanation: Bomine is the only non-metal which exists as a liquid at room temperature.

2. The number of protons in an atom of an element A is 19 then, the number of electron in its ion A⁺ is:

a) 18

b) 19

c) 20

d) 21

Answer: (a) 18

Explanation: In the neutral atom of an element,

3. Bauxite is an ore of

a) Iron

b) Aluminium

c) Mercury

d) Copper

Answer: (b) Aluminium

Explanation: Bauxite is a commercial ore of aluminium which consists largely of hydrated aluminium oxide, Al₂O₃.2H₂O. 

4. The metal which is liquid at room temperature is

a) Bromine

b) Mercury

c) Iodine

d) Potassium

Answer: (b) Mercury

5. The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This process is known as

a) Roasting

b) Smelting

c) Calcination

d) Refining

Answer: (a) Roasting