131. Water kept in an earthen pot is less cool on rainy days than in summer because during the rainy days
(a) the pores in the pot are closed
(b) rain water stops oozing out from the pores
(c) the water that oozes out does not evaporate quickly because of the large percentage of moisture in the air
(d) surface of the pot becomes damp
Ans: (c)
132. Tap water is placed in an open pad and allowed to evaporate. After some time the temperature of water
(a) increases to a great extent
(b) increases slightly
(c) decreases slightly
(d) decreases rapidly
Ans: (c)
133. In hot climatic conditions, the buildings are painted white because
(a) white paint is economical
(b) it does not fade off
(c) it does not crack with higher temperature
(d) white coating is a bad conductor of heat and reflects heat rays that fall on it, thus keeping the inside cool
Ans: (d)
134. The evaporation rate depends on
(a) the nature of the liquid
(b) area of the exposed surface of the liquid
(c) temperature of air and of the liquid
(d) All the above
Ans: (d)
135. The rate of cooling of a hot body depends on
(a) the nature of the radiating surface
(b) area of the radiating surface
(c) temperature difference between the body and the surroundings
(d) All the above
Ans: (d)
136. When we sweat, we feel comfortable under a fan because
(a) the air circulated by the fan is cool
(b) the fan produces convection currents of air
(c) the air circulated by the fan quickens the evaporation of the moisture on our skin
(d) the air takes away the heat from our body
Ans: (c)
137. The hygrometer is an apparatus used for finding the
(a) temperature of air
(b) intensity of light
(c) density of a liquid
(d) relative humidity of the atmosphere
Ans: (d)
138. In a refrigerator, the refrigerant is
(a) Nitrogen
(b) Oxygen
(c) Chlorine
(d) Freon
Ans: (d)
139. Which of the following is known as freon?
(a) Liquid ammonia
(b) Carbon tetrafluoride
(c) Dichloro-difluoro-methane
(d) Sulphur dioxide
Ans: (c)
140. Increase in pressure
(a) has no effect on the boiling point of a liquid
(b) raises the boiling point of a liquid
(c) lowers the boiling point of a liquid
(d) increases the volume of a liquid
Ans: (b)
141. The pressure of air at high altitude is less than the atmospheric pressure at the sea level. Hence the boning point of water at a hill top
(a) is more than at sea level
(b) is equal to that sea level
(c) is less than at sea level
(d) depends on the surrounding temperature
Ans: (c)
142. Increase in pressure
(a) increases the melting point of ice
(b) decreases the melting point of ice
(c) has no effect on the melting point of ice
(d) increases the volume of the ice
Ans: (b)
143. Two tumblers stuck together can be separated by
(a) pouring ice cold water into the inner tumbler
(b) pouring ice cold water on the outer tumbler
(c) pouring hot water into the inner tumbler
(d) dipping both the tumblers in hot water
Ans: (a)
144. Skating on ice is possible because
(a) the surface of ice is smooth
(b) ice is cold
(c) the pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water
(d) the pressure on the ice due to skate raises its melting point
Ans: (c)
145. Of the following types of electromagnetic radiation which has the longest wavelength?
(a) ultraviolet rays
(b) gamma rays
(c) radio waves
(d) infrared waves
Ans: (c)
146. Of the following which has got the highest frequency?
(a) ultraviolet rays
(b) gamma rays
(c) radio waves
(d) infrared waves
Ans: (b)
147. Radio waves sent out by radio stations are reflected by
(a) troposphere
(b) stratosphere
(c) mesosphere
(d) ionosphere
Ans: (d)
148. The maximum range of most TV signals is from 121 to 240 km only because
(a) the curvature of earth limits the range of reception
(b) the signals are weak
(c) the signals are absorbed by air
(d) the antennae are not powerful enough
Ans: (a)
149. Less dew is formed on cloudy nights because
(a) there is no moisture in the atmosphere
(b) clouds absorb the falling dew
(c) objects emit radiant energy very fast on such nights
(d) objects lose less radiant energy
Ans: (d)
150. In a refrigerator cooling is produced by
(a) the ice that deposits on the freezer
(b) the evaporation of a volatile liquid
(c) None of the above
(d) Both (a) and (b)
Ans: (b)