Environmental Chemistry(12th Grade > Chemistry ) Questions and answers for exam Preparation

12th Grade > Chemistry

ENVIRONMENTAL CHEMISTRY MCQs

Total Questions : 40 | Page 4 of 4 pages

Question 31. Which of the followings pair does not consist of greenhouse gases?

Water vapour and CO2
CO and O3
CH4 and Nitrous Oxide
Chloroflurocarbons and CO2

Discuss Question

Answer: Option B. -> CO and O3
:
B
Except CO, all other gases act as greenhouse gas.
Points to remember:Greenhouse gases -

C O_{2}, O_{3}, C H_{4},

Nitrous Oxide and CFC's

Question 32. Which of the following is incorrect?

Chlorofluorocarbons are responsible for ozone layer depletion
Greenhouse effect is responsible for global warming
Ozone layer does not permit infrared radiation from the sun to reach the earth
Acid rains is mostly because of oxides of nitrogen and sulphur

Discuss Question

Answer: Option C. -> Ozone layer does not permit infrared radiation from the sun to reach the earth
:
C
Ozone layer does not allow UV radiation from the sun to reach the earth.

Question 33. Which of the followings pair is not present in acid rain (if any one acid in the given pair is not present, then that pair is considered to be not present)-

H2CO3 and H2SO3
HNO3 and H2CO3
H2SO4 and H3PO4
H2SO3 and H3SO4

Discuss Question

Answer: Option C. -> H2SO4 and H3PO4
:
C
Acid rain is caused due to reaction of water with gaseous oxides present in atmosphere. As oxides of C, N and S are present in the form of

C O_{2}, N O_{x}, S O_{2} a n d S O_{3}

; their corresponding acids are present in acid rain. But

H_{3} P O_{4}

is absent.

Question 34. Assertion (A): Classical smog occurs in cold humid climate and it is acidic as well as reducing in nature.
Reason (R): It is a mixture of smoke, fog and sulphur dioxide.

Both A and R are correct and R is the correct explanation of A.
Both A and R are correct but R is not the correct explanation of A.
A is correct but R are not correct.
A is not correct but R is correct.

Discuss Question

Answer: Option A. -> Both A and R are correct and R is the correct explanation of A.
:
A
Classical smog occurs in cold humid climate. It is a mixture of smoke, fog and sulphur dioxide. Presence of

S O_{2}

makes it both acidic as well as reducing.

Question 35. A brick kiln should not be allowed near an orchard:

To save plants from soil erosion
To save fruits from laborers
To save plants from smoke and toxic gases emitted by kiln
To save plants from transport vehicles

Discuss Question

Answer: Option C. -> To save plants from smoke and toxic gases emitted by kiln
:
C

S O_{2}

gas produced from brick kiln causes death of plants.

Question 36. Excess of which of the followings in drinking water is responsible for disease known as ‘Blue Baby Syndrome’ or ‘Methemoglobinemia’?

F−
NO−3
SO2−4
Cl−

Discuss Question

Answer: Option B. -> NO−3
:
B
The disease ‘Blue Baby Syndrome’ or ‘Methemoglobinemia’ is caused due to presence of excess

N O_{3}^{-}

ion in drinking water.

Question 37. Which of the followings is incorrect? Addition of Phosphate containing fertilizers into water causes –

Decrease in amount of dissolved oxygen in water.
Eutrophication
Increase in fish population
Enhanced growth of algae

Discuss Question

Answer: Option C. -> Increase in fish population
:
C
Addition of phosphates in water enhances algae growth. Such profuse growth of algae covers the water surface and reduces the oxygen concentration in water. It inhibits the growth of living organisms such as fish in water. This process of loss of biodiversity is known as Eutrophication.

Question 38. Which of the following pairs is secondary precursors of photochemical smog –

SO2 and NO2
SO2 and hydrocarbons
NO2 and hydrocarbons
O3 and PAN

Discuss Question

Answer: Option D. -> O3 and PAN
:
D
Photochemical smog does not contain

S O_{2}

. Hence we straight away discard options (a) and (b).

N O_{2}

and hydrocarbons are primary precursors while

O_{3}

, PAN, Formaldehyde, and Acrolein are secondary precursor of photochemical smog.

Question 39. Which of the followings is incorrect about photochemical smog –

It is produced in warm, dry and sunny climate
It is oxidizing in nature.
Ozone gas is one of its constituents.
It is formed in stratosphere.

Discuss Question

Answer: Option D. -> It is formed in stratosphere.
:
D
Photochemical smog is formed in troposphere not in stratosphere. It is produced in warm, dry and sunny climate. It's main constituents are

O_{3}, N O_{2}

and unsaturated carbons. Ozone is formed due to reaction between

N O_{2}

and atmospheric oxygen.

N O_{2} (g) u v - \to N O (g) + O (g)

O (g) + O_{2} (g) \to O_{3} (g)

Question 40. Green chemistry is the branch of chemistry that involves study of processes and products that minimise the use of _____ substances.

useful
hazardous
microscopic
eco-friendly

Discuss Question

Answer: Option B. -> hazardous
:
B
Green chemistry is the study of science dealing with the development of environment friendly technology. It aims to reduce the use and production of hazardous and poisonous chemicals.