Assertion:  UV radiation causes photodissociation of oz

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 Multiple Choice QuestionsMultiple Choice Questions

51.

If  λν,  λx and  λmrepresent the wavelengths of visible light, X-rays and microwaves respectively, then

  • λ m > λ x >  λ ν

  • λv >λm > λx

  • λm> λv > λx

  • λv >  λx >  λm


52.

In gamma ray emission from a nucleus

  • both the neutron number and the proton number change

  • there is no change in the proton number and the neutron number

  • only the neutron number changes

  • only the proton number changes


53.

Which of the following electromagnetic waves have the  smallest wavelength?

  • γ - rays

  • X- rays

  • UV waves

  • infrared rays


54.

X-rays are used in determining the molecular structure of crystalline because

  • its energy is high

  • it can penetrate the material

  • its wavelength is comparable to interatomic distance

  • its frequency is low


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55.

Assertion:  The electromagnetic waves are transverse in nature.

Reason:  Waves of wavelength 10 µm are radiowave and microwave.

  • 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.


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56.

Assertion:  UV radiation causes photodissociation of ozone into O2 and O, thus causing damage to the stratospheric ozone layer. 

Reason:  Ozone hole is resulting in global warming and climate change.

  • 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


C.

If assertion is true but reason is false

UV radiation does not cause photodissociation of ozone into O2 and O instead it takes pan in the formation of ozone into two steps. In the first step, UV radiation breaks apart the two atoms of oxygen and in the second step one of the liberated atoms ( O ) joins another oxygen molecule ( O2 ) to form ozone ( O3 )

          O2 UV radiation  O + O

           O2 + O UV radiation O3                                  ozone

human activities, the ozone layer in the stratosphere becomes start thinning which is also called ozone hole.  Ozone hole is resulting in rain failure, increase in radiation, cancers (skin) and reduction in crop production. Global warming and climate changes are mainly due to green-house gases ( CO2, NOx ). 


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57.

Assertion:  Electromagnetic waves with frequencies smaller than the critical frequencies of ionosphere cannot be used for communication using sky wave propagation. 

Reason: The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.

  • 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.


58.

Assertion: Electromagnetic radiations exert pressure. 

Reason:  Electromagnetic-waves carry both momentum and energy.

  • 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.


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59.

The frequency order for X-rays ( A), γ-rays (B), UV rays (C) is

  • B > A > C

  • A > B  > C

  • C > B > A

  • A > C > B


60.

Assertion:  In electromagnetic waves electric field and magnetic field lines are perpendicular to each other.
Reason: Electric field and magnetic field are self sustaining.

  • 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.


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