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 Multiple Choice QuestionsMultiple Choice Questions

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71.

Photochemical smog formed in congested metropolitan cities mainly consists of:

  • ozone, peroxyacetyl nitrate and NOx

  • smoke, peroxyacetyl nitrate and SO2

  • hydrocarbons, SO2 and CO2

  • hydrocarbons, ozone and SOx


A.

ozone, peroxyacetyl nitrate and NOx

Photochemical smog mainly consists of ozone, pcroxyacetyl nitrate and different oxide of
nitrogen and hydrocarbons released from different engines. 

Nitric oxide or NO is formed by reaction between oxygen and nitrogen. This reacts with air forming nitrogen dioxide (NO2). This gas absorbs light due to which nitric oxide (NO) and a molecule of nascent oxygen [O] are formed.

NO2 NO + [O]

This atomic oxygen reacts with unburnt hydrocarbons to give rise to peroxy radicals which after reaction with oxygen form ozone or reacting with NO2 give rise to peroxyacetyl nitrate (PAN).


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72.

Assertion : Inhabitants close to very busy airports are likely to experience health hazards.

Reason : Sound level of jet aeroplanes usually exceeds 160 dB.

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

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

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


73.

Zooplanktons are :

  • parasites

  • primary producers

  • primary consumers

  • primary decomposers


74.

When one organism is benefited without affecting the other, it is called

  • parasitism

  • commensalism

  • saprophytis

  • symbiosis


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75.

The equation NnNt= B represents, which of the following?

  • Natality

  • Growth rate

  • Mortality

  • All of these


 Multiple Choice QuestionsShort Answer Type

76.

What are mycorrhizae?


 Multiple Choice QuestionsMultiple Choice Questions

77.

Scirpophage incertulus is an example of

  • monophagus pest

  • diphagus pest

  • oligophagus pest

  • polyphagus pest


78.

Which one of the following is a population?

  • A spider and some trapped flies in its web

  • Earthworm that lives in a grassland along with other arthropods

  • All the plants in a forest

  • All the oak trees in a forest


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79.

A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is

  • 10

  • 15

  • 05

  • Zero


80.

A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is

  • ectoparasitism

  • symbiosis

  • commensalism

  • amensalism


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