Physical Properties of Matter

Total Questions: 54

11. A hydrogen inflated polythene is released from the surface of the earth as the balloon rises to an attitude up in the atmosphere it will - [I.A.S. (PRE) 2003]

(a) decrease on size
(b) flatten into disc like shape
(c) increase in size
(d) maintain the same size and shape

Correct Answer: (c) increase in size

Solution:A hydrogen inflated polythene is released from the surface of the earth then the air pressure at the high altitude is reduced thus the balloon will expand until the pressure inside the balloon equals the pressure outside .

12. What happened when a charge is placed on a soap bubble? [U.P.P.C.S.(pre)2019]

(a) its radius increased
(b) its radius decrease
(c) the bubble collapsed
(d) none of the above

Correct Answer: (a) its radius increased

Solution:When some charge is paced on a soap bubble the bubble will expend and its radius is increased because the charge is distribute itself evenly over the surface of the bubble and the repulsion between the same charges will cause it to expend until the surface tension can bring it to equilibrium.This will happen to both positive and negative charged bubbles.

13. Four wires of same material and dimension as shown in below are stretched by a load of same magnitude separately.Which one of them will be elongated maximum? [I.A.S. (PRE) 2007]

(a) wire of 1 m length and 2 mm diameter
(b) wire of 2 m length and 2 mm diameter
(c) wire of 3 m length and 1.5 mm diameter
(d) wire of 1 m length and 1 mm diameter

Correct Answer: (c) wire of 3 m length and 1.5 mm diameter

Solution:All the four wires are made up of the same material therefore they have the equal young modulus (modulus of elasticity)
Y=(f/A)/Δl/L=fL/AΔl=fL/Πr²Δl

∴Δl∝L/r²

thus elongation of these wire is proportional to their lenght and inversely proportional to the square of diameter.so option (c) has the maximum elongation.

14. Consider the following statement - [I.A.S.(PRE)2012]

If there were no phenomenon of capillarity then
1. it would be the difficult to use a kerosene lamp
2. one would not be able to use a straw to consume a soft drink.
3. the blotting paper would fail to function
4. the big trees that we see around would not have grown on the earth.
which of the following statement given above are correct ?

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

Correct Answer: (b) 1,3,and 4 only

Solution:Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to external forces like gravity. Kerosene rises in the wick of the lamp through capillary action. If a person wants to consume the soft drink, he needs to impose some external force by his mouth. As we know capillary action takes place only in the absence of any external force, hence one would not be able to use a straw. Blotting paper also works on the principle of capillary action. It has a large number of pores on its surface which acts like a capillary tube. Nature is an excellent user of capillary action. The fine roots of trees act as capillary tubes, which provide them useful nutrients and water.

15. For which one of the following capillarity is not the only reason ? [I.A.S. (PRE) 1999]

(a) blotting of ink
(b) rising of underground water
(c) spread of water drop on a cotton cloth
(d) rising of water from the roots of a plants to its foliage

Correct Answer: (d) rising of water from the roots of a plants to its foliage

Solution:We can find several example of capillarity in our daily life such as blotting soft ink by blotting paper rising of underground water the spread of water drop cloth rising of kerosene in the wick of the lamp.but the capillarity is not the only reason for rising of water from the roots of a plants to its foliage apart from this transpiration and cohesion is also responsible for this process.

16. Kerosene rises in the wick of the stove is due to - [R.A.S./R.T.S (PRE) 1997]

(a) osmosis
(b) diffusion
(c) surface tension
(d) biogen contraction

Correct Answer: (c) surface tension

Solution:Kerosene oil rising in the wick of the stove is due to the surface tension of oil.The wick of the lamp has many holes which acts as capillaries.so kerosene keeps on rising in the capillaries.

17. In a capillaries tube a fluid rises more as compared to water it is due to : [R.A.S./R.T.S (PRE) 2007]

(a) fluid is more viscus than the water
(b) temperature of fluid is more than that of water
(c) surface tension of fluid is less than that of water
(d) surface tension of the fluid is more than that of water

Correct Answer: (d) surface tension of the fluid is more than that of water

Solution:In a capillary tube liquid rises in proportion with its surface tension.The liquid which has more surface tension would gain more height.

18. When an air bubble at the bottom of lake rises to the top it will - [I.A.S. (PRE) 1996]

(a) increased in size
(b) decreased in size
(c) maintain its size
(d) flatten into a disc like shape

Correct Answer: (a) increased in size

Solution:When a air bubble at the bottom of the lake rises to the top it will increase in size.The pressure of the trapped air in the bubble decrease due to decreasing vertical liquid depth.

19. While travelling by plane the ink of the pen starts to come out - [U.P.P.C.S.(pre) 1992]

(a) due to increase air pressure
(b) due to decrease air pressure
(c) due to increase in volume of ink
(d) due to excessive load.

Correct Answer: (a) due to increase air pressure

Solution:the fountain pen leak at high altitude it is because of low air pressure the ink inside the formation pen has high pressure compared to the low atmosphere so ink flows out of the pen.

20. In automobile hydraulic brakes work on - [Jharkhand P.C.S.(PRE) 2003]

(a) archimedes principle
(b) newton laws of motion
(c) bernoulli's principle
(d) pascal's law

Correct Answer: (d) pascal's law

Solution:Hydraulic brakes, hydraulic press, hydraulic elevator all works on the principle of pascal law which state that the pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all direction throughout he fluid such that the pressure variation remains the same .

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Physical Properties of Matter