Multiple Choice Questions

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Assertion: The resistivity of a semiconductor increases with temperature. 

Reason:  The atoms of a semiconductor vibrate with larger amplitude at higher temperatures thereby increasing its resistivity.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


D.

if both assertion and reason are false statements

With the increase of temperature, the average energy exchanged in a collision increases and so more valence electrons can cross the energy gap, thereby increasing the electron-hole pairs. As in a  semiconductor, conduction occurs mainly through electron-hole pairs, so conductivity increases with increase on temperature. Which in turn implies that the resistivity of a semiconductor decreases with rise in temperature.


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Assertion:  The stars twinkle while the planets do not. 

Reason: The stars are much bigger in size than the planets.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


Assertion: Radioactive nuclei emit  β- particles.

Reason: Electrons exist inside the nucleus.

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

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

  • if assertion is true but reason is false

  • If both assertion and reason are false statements


Assertion: Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate. 

Reason:  According to classical physics all moving electrons radiate.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


Assertion:   Microwave communication is peferred over optical communication. 

Reason: Microwaves provide large number of channels and bandwidth compared to optical signals.

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

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

  • if assertion is true and reason is false

  • if both assertion and reason are false statements


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Assertion:  A beam of charged particles is employed in the treatment of cancer. 

Reason: Charged particles on passing through a material medium lose their energy by causing ionization of the atoms along their path.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


Assertion: Owls can move freely during night. 

Reason: They have large number of rods on their retina.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


Assertion: In high latitudes one sees colourful curtains of light hanging down from high altitudes. 

Reason: The high energy charged particles from the are deflected to polar regions by the magnetic field of the earth.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


Assertion: Neutrons penetrate matter more readily as compared to protons.

Reason: Neutrons are slightly more massive than protons.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


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Assertion: The possibility of an electric bulb fusing is higher at the time of switching on and off.

Reason: Inductive effects produce a surge at the time of switch-off and switch-on.

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

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

  • if assertion is true but reason is false

  • if both assertion and reason are false statements