Which of the following gases is lighter than air?

(A) Carbon dioxide
(B) Oxygen
(C) Ammonia
(D) Chlorine

Amalgams are:

(A) Alloys which contain carbon
(B) Alloys which have great resistance to abrasion
(C) Alloys which contain mercury as one of the contents
(D) Highly coloured alloys

The main important feature of a neutron bomb is that when it is dropped on a city, it would damage­:

(A) Both the living organisms and buildings
(B) The buildings but not the living organisms
(C) The living organisms but spare buildings
(D) None of the above

In which of the following processes light energy is converted into chemical energy?

(A) Respiration
(B) Fermentation
(C) Photosynthesis
(D) Photorespiration

One fathom is equal to:

(A) 6 metres
(B) 6 feet
(C) 60 feet
(D) 100 cm

The picture tube of a black and white T.V. set has only one electron gun that produces the picture on its screen. The number of electron guns, a colour picture tube has, is:

(A) Five
(B) Three
(C) Four
(D) Six

The principle of working of the periscope is based on:

(A) Reflection only
(B) Refraction only
(C) Reflection and refraction
(D) Reflection and interference

A thermostat is:

(A) A device which varies the temperature of a bath.
(B) An instrument by which the accuracy of thermometers is determined.
(C) A device used to maintain a constant temperature of a water bath or an oven.
(D) A modem type of thermoflask which works on the principle of equipartition of heat energy.

Which of the following statements is correct?

(A) Dynamo converts electrical energy into heat energy and electric motor converts mechanical energy into electrical energy.
(B) Dynamo converts mechanical energy into electrical energy and electric motor converts electrical energy into mechanical energy.
(C) Both dynamo and electric motor converts electrical energy into mechanical energy.
(D) Both dynamo and electric motor converts mechanical energy into electrical energy.