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| 28)An object weight maximum in | |||
| air | water | ||
| hydrogen | vacuum | ||
| Answer : | |||
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| 29)Four solid cubes of different metals each one having mass 1kg are weighed in water. | |||
| All cubes weigh equal. | Cube with minimum density weighs minimum. | ||
| Cube with minimum density weighs maximum. | Cube with maximum density weighs minimum. | ||
| Answer : | |||
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| 30)Which one of the following would a hydrogen balloon find easiest to lift. | |||
| 1kg of water. | 1kg of copper. | ||
| 1kg of loosely packed cotton. | All the same. | ||
| Answer : | |||
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| 31)A stone is thrown into a deep lake. As it sinks deeper and deeper into the water, the up-thrust acting on it | |||
| increases | decreases | ||
| first decreases than increases | remain constant | ||
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| 32)Raindrops are spherical due to | |||
| viscisity | surface tension | ||
| continuous evaporation | air friction | ||
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| 33)When two mercury drops are brought into contact, they merge to a bigger drop because liquids have tendency to possess | |||
| minimum volume | maximum surface area | ||
| minimum surface area | maximum volume | ||
| Answer : | |||
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| 34)On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because | |||
| mercury is a metal | density of mercury is greater than that of water | ||
| cohesion of mercury is greater than that of water with glass | cohesion of water is greater than its adhesion with glass | ||
| Answer : | |||
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| 35)Over 90% of the world\'s biomass is in | |||
| tropical rain forest | freshwater wetland | ||
| topsoil | oceans | ||
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| 36)Which one of the following is a source of methane emission into the atmosphere? | |||
| Automobile exhaust fume | Industrial chimney | ||
| Mining | Wetland | ||
| Answer : | |||
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| 37)Which one of the following statements is not correct? | |||
| Trophic dynamics represents the transfer of energy from one trophic level to another in a food chain. | In deeper parts of oceans, primary production remains lmost nil. | ||
| The primary consumers are called autotrophs. | The decomposers are called saprotrophs | ||
| Answer : | |||
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| 38)Carbon dioxide is called a greenhouse gas because | |||
| its concentration remains always higher than other gases. | it is used in photosynthesis. | ||
| it absorbs infrared radiation. | it emits visible radiation. | ||
| Answer : | |||
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| 39)The fossil of Archaeopteryx represents the evidence of origin of | |||
| birds from reptiles. | mammals from reptiles. | ||
| reptiles from amphibians. | Mammals from birds. | ||
| Answer : | |||
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| 40)Lake of atmosphere around the Moon is due to | |||
| low escape velocity of air molecule and low gravitational attraction. | high escape velocity of air molecule and low gravitational attraction. | ||
| low gravitational attraction only | high escape velocity of air molecule only | ||
| Answer : | |||
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| 41)After rising a short distance, the smooth column of smoke from a cigarette breaks up into an irregular and random pattern. In a similar fashion, a stream of fluid flowing past an obstacle breaks up into eddies and vortices which give the flow irregular velocity components transverse to the flow direction. Other examples include the wakes left in water by moving ships, the sound produced by whistling and by wind instruments. These examples are results of | |||
| laminar flow of air. | streamline flow of air. | ||
| turbulent flow of air. | viscus flow at low speed. | ||
| Answer : | |||
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