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Physical Science |
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| 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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