Subject

Physics

Class

NEET Class 12

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

21.

Pressure versus temperature graph of an ideal gas is as shown in figure. Density of the gas at point  A is  ρ0  Density at point B will be

           

  • 34 ρ0

  • 32 ρ0

  • 43 ρ0

  • 0


22.

The latent heat of vaporisation of a substance is always

  • greater than its latent heat of fusion

  • greater than its latent heat of sublimation

  • equal to its latent heat of sublimation

  • less than its latent heat of fusion


Advertisement

23.

A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by   62°C, the efficiency of the engine is doubled. The temperatures of the source and sink are

  • 99oC, 37oC

  • 80oC, 37oC

  • 95oC, 37oC

  • 90oC, 37oC


A.

99oC, 37oC

Maximum efficiency of an engine working between temperatures T2 and T1 is given by the fraction of the heat absorbed by an engine which can be converted into work is known as efficiency of the heat engine.

Mathematically

Efficiency η = T2 - T1T2

               η = 16

⇒   6 T2 - 6 T1 = T2

∴   T2 = 1.2 T1                 .....(i)

Where  T2 is the source temperature and T1 is the sink temperature

If the sink temperature ( T1 ) is reduced by 62oC, the efficiency gets doubled i.e

     η = T2 - T1 - 62T2

         = 2 × 16

     η  = 26

    6 T2 - 6 T1 + 372 = 2 T2

⇒  6 T2 - 2 T2 - 6 T1 + 372 = 0

⇒  4 T2 - 6 T1 + 372 = 0

Substituting the value of T2 from equatin (i), we will get

   4 ( 1.2 T1- 6 T1 + 372 = 0

    4.8 T1 - 6 T1 + 372 = 0

⇒   372 = 1.2 T1

⇒       T1 = 310 K

Therefore, 

       T2 = 1.2 × 310

         T2 = 372 k

Hence, the temperature of the source ane the sink is 372 K i.e 99oC  and 310 K i.e  37oC respectively.


Advertisement
24.

Graph of specific heat at constant volume for a monoatomic gas is

  •  

  •  


Advertisement
25.

A liquid is kept in a cylindrical vessel which is being rotated about a vertical axis through the centre of the circular base. If the radius of the vessel is r and angular velocity of rotation is w, then the difference in the heights of the liquid at the centre of the vessel and the edge is

  • r ω2 g

  • r2 ω22 g

  • 2 gr ω

  • ω22 gr2


26.

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of water in the capillary tube is 5 g. Another capillary tube of radius 2 r is immersed in water. The mass of water that will rise in this tube is

  • 2.5 g

  • 5.0 g

  • 10 g

  • 20 g


27.

Five sinusoidal waves have the same frequency 500 Hz but their amplitudes are in the ratio 2 : 12 : 12 : 1 : 1 and their phase angles 0, π6,  π3,  π2  and  π respectively. The phase angle of resultant wave obtained by the superposition of these five waves is

  • 30o

  • 45o

  • 60o

  • 90o


28.

The second overtone of an open pipe has the same frequency as the first overtone of a closed pipe 2 m long. The length of the open pipe is

  • 8 m

  • 4 m

  • 2 m

  • 1 m


Advertisement
29.

Let T1 and T2 be the time periods of springs A and B when mass M is suspended from one ·end of each spring. If both springs are taken in series and the same mass M is suspended from the series combination, the time period is T then

  • T1 + T2 +T3

  • 1T  = 1T1 + 1T2

  • T2T1 2 + T2 2

  • 1T2 = 1T1 2 + 1T2


30.

Assertion:  Water kept in an open vessel will quickly evaporate on the surface of the moon. 

Reason:  The temperature at the surface of the moon is much higher than boiling point of water.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


Advertisement