Physical Properties of Matter

51. Why it is easier to swim in the sea than in a river ? [U.P Lower Sub.(PRE) 2002]

(a) the sea water is salty
(b) the sea water is deep
(c) the sea water is heavier
(d) the sea water is lighter

Correct Answer: (a) the sea water is salty

Solution:It is easier to swim in sea water than in a river because the sea water contains salts which increase the density of water and also increase its upthrust so the chances of sinking get reduced and one can easily swim in such water.

52. A body weight is highest in which among the following ? [U.P.P.C.S.(MAINS) 2017]

(a) air
(b) water
(c) hydrogen
(d) nitrogen

Correct Answer: (c) hydrogen

Solution:The upthrust force or buoyant force in hydrogen will be less than the other matters because it is the lightest gas. so the option (c) is the correct answer.

53. When the ship enters a sea from a river what happens ? [U.P Lower Sub.(PRE) 2004, U.P.P.C.S.(pre) 1992]

(a) it rises a little
(b) it remains at the same level
(c) it sinks a little
(d) it immersed in the bottom of the sea

Correct Answer: (a) it rises a little

Solution:When a ship enters a sea from a river the ship is elevated due to the higher density of salty sea water than the water.

54. Assertion (A) :when a ship enters a sea from it rises a little . Reason (R) : The density of sea water is greater than that of the river water.In the context of the above statement which of the following is true ; [U.P.P.C.S.(pre) 2003, U.P.U.D.A./L.D.A.(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: (a) both (A) and (R) are true and (R) is the correct explanation of (A)

Solution:When a ship enters a sea from a river the ship is elevated due to the higher density of salty sea water than the water.

Physical Properties of Matter