In refrigerator, cooling is produced by _____.

1. 1. the sudden expansion of a compressed gas
   2. the evaporation of a volatile liquid
   3. The ice which deposits on the freezer
   4. None of these

Tube light works on the principle of _____.

1. 1. Discharge of electricity through gases
   2. Heating effect of current
   3. Chemical effect of current
   4. Magnetic effect of current

Nitrogen is prepared in the laboratory by heating _____.

1. 1. The mixture of ammonium chloride and sodium nitrite
   2. Ammonium sulphate
   3. The mixture of ammonium chloride and calcium oxide
   4. Aluminium nitrate

The material used for bleaching paper pulp is _____.

1. 1. Alum
   2. Lime
   3. Caustic soda
   4. Sodium

Liquefied petroleum gas consists of mainly _____.

1. 1. Methane, butane and propane
   2. Methane, ethane and hexane
   3. Ethane, hexane and nonane
   4. None of the above

Mother’s milk is preferred to cow’s milk because it contains _____.

1. 1. More lipids and less fats
   2. Less lipids and more fats
   3. Less fats and less lipids
   4. More fats and more lipids

Why do the electricians wear rubber gloves while touching wires?

1. 1. Rubber is a bad conductor of electricity and electrician does not get electrocuted
   2. With rubber gloves they can hold wires properly
   3. It helps in the smooth flow of the current
   4. None of the above

Why are two blankets warmer than one?

1. 1. Two blankets enclose air which does not allow the cold to penetrate
   2. Two blankets have more wool and so warmer
   3. Two blankets compress the air in between the body and the blankets and this compression produces heat
   4. None of the above

How does a man die by touching a live wire?

1. 1. The current stops the flow of blood through the heart
   2. It affects the nervous system and so kills brain cells
   3. The current passes into the earth through the man’s body. As the circuit is complete it burns the body
   4. None of the above

When wind blows at high velocity, roof tops are blown off because pressure _____.

1. 1. Is exerted by air form outside
   2. Outside is more than inside the roof
   3. Inside is more than outside the roof
   4. Increase due to wind velocity