Environmental Chemistry — Page 7 | NEET Chemistry

Q61

The reaction that is NOT involved in the ozone layer depletion mechanism in the stratosphere is :

A

Cl\mathop O\limits^ \bullet \left( g \right) + O\left( g \right) \to \mathop C\limits^ \bullet l\left( g \right) + {O_2}(g)

B

C{F_2}C{l_2}\left( g \right)\,\overset{{uv}}\longrightarrow \mathop {\,C}\limits^ \bullet l\left( g \right) + \mathop C\limits^ \bullet {F_2}Cl\left( g \right)

C

C{H_4} + 2{O_3}\, \to \,3C{H_2} = O + 3{H_2}O

D

HOCl\left( g \right)\,\overset{{hv}}\longrightarrow \,\mathop O\limits^ \bullet H\left( g \right) + \mathop C\limits^ \bullet l\left( g \right)

Correct Answer

Option C

Solution

Ozone layer depletion mechanism occurs with Chlorofluorocarbons and involves chlorine radical.

In CH4, there is no Cl so it is not involved in the ozone layer depletion mechanism

Q62

Given below are two statements : Statement I : Chlorofluoro breakdown by radiation in the visible energy region and release chlorine gas in the atmosphere which then reacts with stratospheric ozone. Statement II : Atmospheric ozone reacts with nitric oxide to give nitrogen and oxygen gases, which add to the atmosphere. For the above statements choose the correct answer from the options given below :

A Statement I is incorrect but Statement II is true

B Both Statement I and II are false

C Statement I is correct but Statement II is false

D Both Statement I and II are correct

Correct Answer

Option B

Solution

Statement (1) CFCs are broken down by powerful UV radiation and releases chlorine free radical which reacts with ozone and start chain reaction.

C{F_2}C{l_2}_{(g)}\overset{{UV}}\longrightarrow \mathop C\limits^ \bullet {l_g} + \mathop C\limits^ \bullet {F_2}C{l_{(g)}}

\mathop C\limits^ \bullet {l_{(g)}} + {O_{3(g)}} \to \mathop C\limits^ \bullet l{O_{(g)}} + {O_{2(g)}}

\mathop C\limits^ \bullet l{O_{(g)}} + {O_{(g)}} \to \mathop C\limits^ \bullet {l_{(g)}} + {O_{2(g)}}

Statement (2) Atmosphere ozone reacts with nitric oxide to produce nitrogen dioxide and oxygen.

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

Q63

Water filled in two glasses A and B have BOD values of 10 and 20, respectively. The correct statement regarding them, is :

A B is more polluted than A.

B A is suitable for drinking, whereas B is not .

C Both A and B are suitable for dirnking

D A is more polluted than B.

Correct Answer

Option A

Solution

Two glasses ''A'' and ''B'' have BOD values 10 and ''20'', respectively.

Hence glasses ''B'' is more polluted than glasses ''A''.

Q64

The acid that is believed to be mainly responsible for the damage of Taj Mahal is :

A sulfuric acid.

B hydrofluoric acid.

C phosphoric acid.

D hydrochloric acid.

Correct Answer

Option A

Solution

CaCO3 + H2SO4 $\to$ CaSO4 + H2O + CO2 Industries like oil refinery releases SO2 which causes air pollution.

It reacts with water to form acid rain when SO2 mix with water it forms H2SO4 (Sulphuric acid).

Q65

The statement that is not true about ozone is :

A In the stratosphere, CFCs release chlorine free radicals (Cl) which reacts with O3 to give chlorine dioxide radicals

B It is a toxic gas and its reaction with NO gives NO2.

C In the atmosphere, it is depleted by CFCs

D In the stratosphere, it forms a protective shield against UV radiation

Correct Answer

Option A

Solution

In the stratosphere, CFCs release chlorine free radical (

\mathop {Cl}\limits^ \bullet

). CF2Cl2(g)

\overset{{UV}}\longrightarrow

\mathop {Cl}\limits^ \bullet

(g) +

\mathop {Cl}\limits^ \bullet

F2Cl(g) Which react with O3 to give chlorine oxide (Cl

\mathop O\limits^ \bullet

) radical not chlorine dioxide (Cl

\mathop O\limits^ \bullet

2) radical.

\mathop {Cl}\limits^ \bullet

(g) + O3(g) $\to$ Cl

\mathop O\limits^ \bullet

(g) + O2(g)

Q66

Identify the pollutant gases largely responsible for the discoloured and lustreless nature of marble of the Taj Mahal.

A O3 and CO2

B CO2 and NO2

C SO2 and NO2

D SO2 and O3

Correct Answer

Option C

Solution

SO2 and NO2 are responsible for the discoloured and lustreless nature of marble.

Q67

The deposition of X and Y on ground surfaces is referred as wet and dry depositions, respectively. X and Y are :

A X = Ammonium salts, Y = CO2

B X = SO2, Y = Ammonium salts

C X = Ammonium salts, Y = SO2

D X = CO2, Y = SO2

Correct Answer

Option C

Solution

Oxides of nitrogen and sulphur are acidic and settle down on ground as dry deposition.

Ammonium salts in rain drops result in wet deposition.

Q68

In stratosphere most of the ozone formation is assisted by :

A cosmic rays

B

\gamma

-rays

C ultraviolet radiation

D visible radiations

Correct Answer

Option C

Solution

Ozone in the stratosphere is a product of UV radiations acting on dioxygen (O2) molecules.

{O_2}(g)\overset{{UV}}\longrightarrow O(g) + O(g)

O(g) + {O_2}(g)

\overset{{UV}}\rightleftharpoons

{O_3}(g)

Q69

The primary pollutant that leads to photochemical smog is :

A acrolein

B ozone

C sulphur dioxide

D nitrogen oxides

Correct Answer

Option D

Solution

Photochemical smog contains oxides of nitrogen.

Q70

The layer of atmosphere between 10 km to 50 km above the sea level is called as :

A mesosphere

B thermosphere

C troposphere

D stratosphere

Correct Answer

Option D

Solution

Between 10-50 km above sea level is the lowest level which is called stratosphere.