Physical Properties of Matter

Total Questions: 54

31. Increasing the amount of a substance does not change its - [U.P.P.C.S.(pre) 1992]

(a) volume
(b) weight
(c) density
(d) density

Correct Answer: (d) density

Solution:increasing the amount of substance does not change its density of an object depends on its mass and volume.density can be found by using the equation :density=mass/volume

32. When water is heated from the 0°c to 10°c.its volume : [I.A.S. (PRE) 2001]

(a) increase
(b) decrease
(c) does not change
(d) first increase and then decrease

Correct Answer: (d) first increase and then decrease

Solution:An increase in temperature increase the volume of a most of the liquid slightly and consequently decrease the liquid density.But the behaviour of water from the 0 to 4 is just opposite.When water is heated 0 to 4 then there is a decrease in volume and increase in a density but when we cross the limit of 4 then again it behaves like other ordinary liquid.which means its volume increase and density decrease.Thus when water is heated from 0 to 10 degree its volume first decrease and then increase.

33. What changes will the volume of water show if the temperature is lowered from 9°c to 3°c : [U.P.P.C.S.(pre) 1997]

(a) the volume will not change
(b) the volume will first increase then decrease
(c) the volume will first decrease then increase
(d) water will freeze

Correct Answer: (c) the volume will first decrease then increase

Solution:If the temperature of water is lowered from 9°c to 4°c then density is maximum at 4°c .Density is inversely proportional to volume therefore till 4°c density increase in which result in decrease in volume and later (4°c to 3°c) reduction in density would cause an increase in volume.

34. The density of the water will reach its maximum value at the temperature of - [R.A.S./R.T.S (PRE) 1992]

(a) 0°c
(b) 4°c
(c) 50°c
(d) 100°c

Correct Answer: (b) 4°c

Solution:The mass of any substance while heating remains the same however its volume increase.Thus its density decrease but the water exhibits an anomalous expansion on cooling and contraction on heating within a specific range of temperature .When water at 0°c is heated it is observed that it contract between 0°c to 4°c.hence the density of water is maximum at 4°c.

35. At which temperature density of water is maximum ? [43th B.P.S.C. (PRE) 1999, 42th B.P.S.C. (PRE)1998, U.P.P.C.S.(mains) 2008]

(a) 4°c
(b) 0°c
(c) -4°c
(d) -8°c

Correct Answer: (a) 4°c

36. The maximum density of the water is at- [U.P.P.C.S.(MAINS) 2015]

(a) 373 kelvin
(b) 277 kelvin
(c) 273 kelvin
(d) 269 kelvin

Correct Answer: (b) 277 kelvin

Solution:The density of water increase with the temperature but the volume decrease. At the 4°c the volume of water is low and density is maximum.Conversion of celsius in kelvin
K=C+273
=4+273=277
so the density of water is maximum at 277k.

37. What is law in which under the same condition of temperature and pressure equal volume of same gases contain equal number of molecules? [67th B.P.S.C. (PRE)(RE.EXAM) 2022]

(a) Coriolis law
(b) Graham law
(c) Pascals law
(d) Avogadro law
(e) None of the above /more than one of the above

Correct Answer: (d) Avogadro law

Solution:Avogadro law states that under the same condition of temperature and pressure equal to the volume of different gases contains an equal number of molecules.For a given mass of an ideal gas the volume and the amount moles of the gas are directly proportional if the temperature and pressure are constant.The law is approximately valid for real gases at the sufficiently low pressure and high temperature.

38. In which of the following condition distance between molecules of carbon dioxide filled in container may increase? [Chhattisgarh P.C.S.(PRE) 2021]

1. on the increasing the volume of container
2. on leakage of some carbon dioxide gas from the container
3. on increasing air pressure in the container
4. on adding more carbon dioxide gas in container without changing its size.

(a) 2 and 3
(b) 3 and 4
(c) 1 and 3
(d) 1 and 2

Correct Answer: (d) 1 and 2

Solution:Gases do not have a definite volume and can occupy any amount of space available and on leakage of some carbon dioxide gas from the container the distance between molecules of carbon dioxide filled in a container will increase.It will decrease on increasing air pressure or on adding more carbon dioxide in container.

39. If a gas is compared to half to its original volume at the 27°c to what temperature should it be heated to make it occupy its original volume? [I.A.S. (PRE) 1994]

(a) 327°c
(b) 600°c
(c) 54°c
(d) 300°c

Correct Answer: (a) 327°c

Solution:according to the law of

from the formula V1/V2=T1/T2

V1=V/2 and V2=V (given)

T1=273+27=300K

T2=?

V/2/V=300/T2⇒T2=600K

∴ T2=600-273=327°c

40. Assertion (A) : An iron ball floats on mercury but gets immersed in water . Reason (R) : The specific gravity of iron is more than that of mercury. [I.A.S. (PRE) 2002]

(a) both (A) and (R) are true and (R) is the correct explanation of (A)
(b) both (A) and (R) are true and (R) is not the correct explanation
(c) (A) is true but (R) is false
(d) (A) is false but (R) is true

Correct Answer: (c) (A) is true but (R) is false

Solution:An iron ball 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.Thus statement (A) is correct but the reason (R) is incorrect.

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Physical Properties of Matter