Physical Properties of Matter

Total Questions: 54

41. Why does an iron nail float on mercury while it sinks in water ? [U.P.P.C.S.(pre) 1994]

(a) due to less chemical interaction of iron with the mercury than it is with water.
(b) Iron is heavier than the water and higher than mercury.
(c) Iron has greater density than the water and lesser than mercury.
(d) mercury is heavier than the water.

Correct Answer: (c) Iron has greater density than the water and lesser than mercury.

Solution:An iron nail floats on the mercury but gets immersed in the water because the relative density of mercury is greater than relative density of iron.However iron has a higher density than the water so its get immersed in water

42. A needle sinks in water where as a ship made of iron floats on it because : [U.P Lower Sub. (SPL) (PRE) 2004]

(a) the edge of the needle is pointed
(b) the ship is flat
(c) the ship drives by a powerful engine.
(d) relative density of the needle is greater than that of water displayed by it

Correct Answer: (d) relative density of the needle is greater than that of water displayed by it

Solution:Relative density is defined as the ratio of the density of a particular substance with that of water the relative density of pure water is 1. Th substance having the relative density less than the 1 will float in water while substance having the relative density more than 1 will sink in water.The ship designed in such a way that its relative density is less than the density of water but the density of iron needle is much larger than the water so it sinks easily.

43. An iron needle will floats on the surface of water due to - [U.P.P.C.S.(MAINS) 2012]

(a) upthrust of water
(b) surface tension
(c) viscosity
(d) gravitational force

Correct Answer: (b) surface tension

Solution:An iron needle can float on water due to the surface tension of water because upward force on the needle due to surface tension balances the weight of the needle.

44. While lifting a bucket of water from a well we feel that the bucket : [U.P.P.C.S.(pre) 2009]

(a) become heavier above the surface of water
(b) become lighter above the surface of water
(c) loses stability on coming out of the water
(d) has gained mass on coming out of water

Correct Answer: (a) become heavier above the surface of water

Solution:According to the Archimedes principle of flotation object appears to be heavier in the air than inside the water or they appears to be less heavy in water.it is because water exerts an upwards force on the objects immersed in it.This reduction is equal to the weight of the fluid that body displaces.

45. 200 gm of water is filled in a weightless balloon its weight in water will be [U.P.R.O./A.R.O.(MAINS) 2014]

(a) zero
(b) 100 gm
(c) 200 gm
(d) 400 gm

Correct Answer: (a) zero

Solution:weight of the balloon in water = weight -upthrust
=200-200=0
the balloon is weightless.

46. The clouds float in the atmosphere because of their low : [I.A.S. (PRE) 1995]

(a) temperature
(b) velocity
(c) pressure
(d) density

Correct Answer: (d) density

Solution:Clouds form when the invisible water vapour in the air condenses into visible water droplets.They are so small that the effect of gravity on them is negligible.Thus the clouds float in the atmosphere because of their low density.

47. While floating in a sea what part of an iceberg is above the surface of the sea ? [U.P.P.C.S.(pre) 2005]

(a) 1/9
(b) 1/10
(c) 1/6
(d) 1/4

Correct Answer: (a) 1/9

Solution:When pure water changes into the ice berg at 4 degree the density of ice so formed is 9/10th of the density of water.Therefore in pure water 90 % part of the ice must be below the surface of the water and remaining 10% part must be above the surface .Sea water has high density (salty) water but the ice formed by its pure and not salty. Therefore while the floating in a sea about 1/8th and 1/9th part of an iceberg is above the surface of the sea.

48. An ice cube is floating in a glass of a water. What happened to the water level when the ice melts it- [M.P.P.C.S.(PRE) 2008]

(a) rises
(b) falls
(c) remains the same
(d) first rises and then falls

Correct Answer: (c) remains the same

Solution:According to Archimedes principle floating object displaces an amount of water equal to its own weight thus the water level remains the same when the ice cube melts.

49. A piece of a ice is floating in a beaker containing water up to its brim.When whole of the ice melts: [67th B.P.S.C. (PRE) 2022]

(a) the water will spill on the floor
(b) the level of water will come down in the beaker
(c) the level of water will first fall and then it will spill out of the beaker
(d) the water level is not change
(e) none of the above / more than one of the above

Correct Answer: (d) the water level is not change

Solution:According to Archimedes principle floating object displaces an amount of water equal to its own weight thus the water level remains the same when the ice cube melts.

50. A body floats at 4 degree water. If temperature reaches 100 degree then- [M.P.P.C.S.(PRE) 1999]

(a) the body will sink
(b) no change
(c) more part of the body will submerged
(d) the body will float freely

Correct Answer: (a) the body will sink

Solution:When the water is heated its density decreases the density of the water at 100 degree is at the lowest so the body will sink water density is maximum at 4 degree so the body floats.

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Physical Properties of Matter