CO is a pollutant because

• it reacts with O₂

• it inhibits glycolysis

• it reacts with haemoglobin

• it makes nervous system inactive

Which country has the greatest contribution for the hole formation in ozone layer?

• USA

• Germany

• Russia

• Japan

A large quantity of urban sewage is drained into nearby village river. Which among the given conditions would happen after mixing of sewage into the river

(i) Biochemical oxygen demand (BOD) of receiving water body increases.

(ii) Dissolved oxygen of receiving water body decreases.

(iii) It will not cause mortality among fishes and other aquatic creatures.

(iv) It will lead to nutrient enrichment of receiving water body.

• (i), (ii) and (iii)

• (i), (ii) and (iv)

• (ii) and (iii) only

• (iii) and (iv) only

The gases that produce green house gases are

• CH₄, CFCs, CO₂

• CO₂, N₂O, H₂

• CFCs, NO₂, O₂

• CO₂, N₂, water vapour

Which of the following statement is correct about DDT

• It is a biomagnifying biodegradable pollutant

• It is non biomagnifying biodegradable pollutant

• It is biomagnifying non biodegradable pollutant

• It is not a pollutant

Plants do not get benefit from

• N₂ in air

• O₂ in air

• CO₂ in air

• O₃ in air

One greenhouse gas contributes 14% to total global warming and another contributes 6%. These are respectively identified as

• N₂O and CO₂

• CFCs and N₂O

• methane and CO₂

• methane and CFCs

Assertion: Secondary air pollutants are formed by interaction among the primary pollutants and are more toxic.

Reason: DDT is a secondary air pollutant.

• 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.

Assertion: BOD of a river polluted by sewage is more than 20 ppm.

Reason: Polluted river contains excess of organic matter.

• 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.

Photosynthetic Active Radiation (PAR) has the following range of wavelengths

• 400- 700 nm

• 450- 950 nm

• 340- 450 nm

• 500- 600 nm