Physical Science

146)In a sprayer the liquid rises in the tube due to
capillarity low pressure at the upper end
ecapporation None of these
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147)When two mercury drops are brought into contact, they merge to form a bigger drop because liquids have a tendency to possess
maximum volume maximum area
minimum potential energy maximum potential energy
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148)The science dealing with the study of phenomena at very low temperature is known as
refrigenics cytogenics
crytogenics frozenics
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149)The atmospheric pressure on us is enormous yet we do not feel it because
Our blood exerts a slightly more pressure then the atmosphere our bones are very strong and withstand the pressure
the surface are of our head is small we are used to it
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150)If water in a lake were to behave like other liquids, then in extremely cold weather it would freeze
from top to bottom bottom to top
at the same throughout the depth None of these
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151)By which of the following process heat is transmitted from the filament of a evacuated electronic bulb to glass
conduction convection
radition None of these
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152)Hot coffee is poured simultaneously in four metallic tumblers painted outside with different types of paints. After some time, the coffee will be found coldest in the tumble painted
shining white rough white
shining black rough black
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153)In a cup, tea cools from 90C to 80C in exactly one minute. It will cool from 70C to 60C in
more than one minute exactly one minute
nearly one minute less than one minute
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154)For a given liquid, the rate of evaporation depends on
the surface area temperature of the liquid
air temperature all of these
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155)Why earthenware keep water cooler
earthenware has high heat capacity water oozing out of the pores evaporates
earthenware absorbs heat from water earthenware is a good heat radiator
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156)During summer, we feel comfortable under a fan because it
produces convection currents set the air in motion, thereby increase the evaporation of sweat.
throws cool air on us produces air which takes heat away from us
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157)Why we should wear light coloured cloths during summer?
light colour is good radiator of heat light colour soak sweat faster
light colour absorbs less heat light colour allow body heat escape faster
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158)Scalding with steam is more severe than scalding with boiling water because
steam can penetrate the skin steam at higher temperature
steam is at higher pressure steam contains more energy than boiling water
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159)One feels cold after a dip in sea water due to
the evaporation of water on the body the deposition of salt on the body
convection currents the difference in temperature between land and sea
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160)Why does the surface water of a pond remain cool in a hot day?
heat absorbed at the surface is transmitted downwards water evaporated at the surface and evaporation causes cooling
water in contact with the bottom of the pond become cooler and rises due to convection None of these
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