Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Which of the following diagrams represents the variation of electric field vector with time for a circularly polarized light?


12.

Three objects coloured black, gray and white can withstand hostile conditions upto 2800°C. These objects are thrown into a furnace where each of them attains a temperature of 2000°C. Which object will glow brightest?

  • The white object

  • The black object

  • All glow with equal brightness

  • Gray object


13.

Two balloons are filled, on with pure He gas and other by air, respectively. If the pressure and temperature of these balloons arc same then the number of molecules per unit volume is

  • more in the He filled balloon

  • same in both balloons

  • more in air filled balloon

  • in the ratio of 1 : 4


14.

When a guitar string is sounded with a 440 Hz tuning fork, a beat frequency of 5 Hz is heard. If the experiment is repeated with a tuning fork of 437 Hz, the beat frequency is 8 Hz. The string frequency (Hz) is

  • 445

  • 435

  • 429

  • 448


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15.

When you make ice cubes, the entropy of water

  • does not change

  • increase

  • decreases

  • may either increase or decrease depending on the process used


16.

A bimetallic strip consists of metals X and Y. It is mounted rigidly at the base as shown. The metal X has a higher coefficient of expansion compared to that for metal Y. When the bimetallic strip is placed in a cold bath

  • it will bend towards the right

  • it will bend towards the left

  • it will not bend but shrink

  • it will neither bend or shrink


17.

For a wave propagating in a medium, identify the property that is independent of the others.

  • Velocity

  • Wavelength

  • Frequency

  • All these depend on each other


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18.

Assertion:  In an isolated system the entropy increases. 

Reason: The processes in an isolated system are adiabatic.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


B.

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

Since, heat flow from hotter to colder bodies is irreversible, reversible processes must involve heat flow between bodies of the same temperature. It follows that any entropy change of the system must be exactly balanced by that of the  heat bath which provided the heat.  Thus, the entropy change of the universe during reversible processes is  zero  during for  a  reversible, adiabatic process is  zero. But  note that he both quantities are needed; the entropy of a non-isolated system  change during a reversible process ( and the entropy change of the surrounding will compensate), and reversible change to an isolated system will increase the entropy.  Hence option (b) is true.

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19.

Assertion:  The root mean square and most probable speeds of the molecules in a gas are the same. 

Reason:  The Maxwell distribution for the speed of molecules in a gas is symmetrical.

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

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

  • If assertion is true, but reason is false

  • Both assertion and  reason are false statements


20.

Assertion: Use of ball bearings between two moving parts of a machine is a common practice. 

Reason:  Ball bearings reduce vibrations and provide good stability.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


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