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Environmental Chemistry

Short Answer Type

61.

How does hydrocarbon cause pollution? Discuss its harmful effects.

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Long Answer Type

62.

Discuss the various chemical reactions occurring in the atmosphere ?

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63. Justify the statement that ozone layer is called ‘earth’s protective umbrella.’
Or
How will you explain the formation of the ozone layer in the atmosphere?

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64.

What are the reactions involved for ozone layer depletion in the stratosphere?

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65.

What do you mean by ozone hole? What are its consequences?

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Short Answer Type

66.

How will you protect the ozone layer ?

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Long Answer Type

67.

What is smog? Explain its two types.

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Short Answer Type

68.

What is smog? How is classical smog different from photochemical smog?

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Long Answer Type

69.

Write down the reactions involved during the formation of photochemical smog.
Or
Discuss the mechanism of photochemical smog formation.

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70.
What are the harmful effects of photochemical smog and how can these be controlled ?

Harmful effects of photochemical smog:

(i) During the formation of photochemical smog, concentration of ozone, peroxyacylnitrate (PAN), aldehydes (RCHO) and ketones (R₂CO) build up in the atmosphere. All these compounds produce irritation in the eyes and also in the respiratory system.

(ii) They also damage many materials.

(iii) Ozone is particularly destructive to rubber.

(iv) NO₂ present gives a brown colour to the photochemical smog which reduces visibility.

Control of photochemical smog: Photochemical smog can be controlled or suppressed by:

(i) Installation of efficient catalytic converters in the automobiles to reduce photochemical smog i.e. it prevents the release of nitrogen oxides and hydrocarbon to the atmosphere.

(ii) Certain compounds which trap free radicals. When these compounds are sprayed in the atmosphere, they generate free radicals which readily combine with free radical precursors of photochemical smog.

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