Question

Give reasons for the following. 

1. Aluminium foils are used to warp food items. 

2. Immersion rods for heating liquids are made up of metallic substances.

3. A doctor prescribed a tablet to a patient suffering from iron deficiency. The tablet does not look like iron. 

4. Sodium and potassium are stored in kerosene. 

5. Mercury is used in thermometers.

Answer 1

1. Aluminium is malleable, soft and does not react with food items, so it is used to wrap food items. 

2. Metals are good conductor of heat and electricity, so immersion rods are made up of metallic substances. 

3. It doesn’t look like iron, iron tablets does not contains iron metal, rather it contains iron salts like ferrous sulphate, ferrous citrate etc. 

4. Sodium and potassium are very reactive, they react with air and water, so they are stored in kerosene.

5. Mercury is used in thermometers and barometers because of its high density and uniform expansion at different temperature.