Environmental Chemistry (Optional for JEE Main) JEE Main Chemistry: Authentic Shift PYQs (2021-2026) with 2.5-Min Shortcut Tricks & Trap Defense

Correct Answer: c

Explanation: O$_{3}$ $\begin{matrix}\text{Nitrogen}\&\text{nbsp};\text{dioxide}\&\text{nbsp}; \left(NO_{2}\right) \textrm{ } can \textrm{ } be \textrm{ } broken \textrm{ } down \textrm{ } by \textrm{ } sunlight \textrm{ } to \textrm{ } form \textrm{ } nitric \textrm{ } oxide \\ \left(NO\right) \textrm{ } and \textrm{ } an \textrm{ } oxygen \textrm{ } radical \textrm{ } \left(O\right) : \\ 1 \left.\right) \textrm{ } NO_{2} \textrm{ } + \textrm{ } sunlight \textrm{ } \rightarrow \textrm{ } NO \textrm{ } + \textrm{ } O \\ Oxygen \textrm{ } radicals \textrm{ } can \textrm{ } then \textrm{ } react \textrm{ } with \textrm{ } atmospheric \textrm{ } oxygen \textrm{ } \left(O_{2}\right) \textrm{ } to \textrm{ } form \textrm{ } ozone \textrm{ } \left(O_{3}\right) \\ 2 \left.\right) \textrm{ } O \textrm{ } + \textrm{ } O_{2} \textrm{ } \rightarrow \textrm{ } O_{3} \\ Ozone \textrm{ } is \textrm{ } consumed \textrm{ } by \textrm{ } nitric \textrm{ } oxide \textrm{ } to \textrm{ } produce \textrm{ } nitrogen \textrm{ } dioxide \textrm{ } and \textrm{ } oxygen : \\ 3 \left.\right) \textrm{ } O_{3} \textrm{ } + \textrm{ } NO \textrm{ } \rightarrow \textrm{ } NO_{2} \textrm{ } + \textrm{ } O_{2} \\ Harmful \textrm{ } products \textrm{ } such \textrm{ } as \textrm{ } PAN , \textrm{ } are \textrm{ } produced \textrm{ } by \textrm{ } reactions \textrm{ } nitrogen \textrm{ } dioxide \textrm{ } \\ with \textrm{ }\text{various}\textrm{ }\text{hydrocarbons}\textrm{ } \left(R\right) , \textrm{ } which \textrm{ } are \textrm{ } compounds \textrm{ } made \textrm{ } from \textrm{ } carbon , \textrm{ } \\ hydrogen \textrm{ } and \textrm{ } other \textrm{ }\text{substances}: \\ \text{4})\textrm{ }\text{NO}_{2} \textrm{ } + \textrm{ } R \textrm{ } \rightarrow \textrm{ } products \textrm{ } as \textrm{ } PAN\end{matrix}$

Correct Answer: d

Explanation: Statement I , II both are false Classical smog is also called reducing smog as it acts as a reducing agent. The reducing character is due to presence of sulphur dioxide and carbon (soot) particles. Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight.

Correct Answer: N/A

Explanation: Excess $NO_{2}   and   SO_{2}$ from burning fossil fuels $\&\text{nbsp};\text{Acid rain refers to the several ways in which acids from the atmosphere are deposited on the earth}.\text{ It includes}\&\text{nbsp};$ $\&\text{nbsp};\text{wet and dry deposition}.\text{ Wet deposition includes the acidic water received through rain},\text{ fog and snow}.\text{ Dry deposition}\&\text{nbsp};$ $\&\text{nbsp};\text{refers to the windblown acidic gases and particles in the atmosphere which settle down on the ground}.\&\text{nbsp};$ $\&\text{nbsp};\text{Sulfur dioxide is the major constituent in the emission when sulfur}-\text{containing coal is burnt}.\text{ It is also emitted by the}\&\text{nbsp};$ $\&\text{nbsp};\text{ore smelters and oil refineries}.\text{ Its high concentration in the air causes severe respiratory problems like asthma},\&\text{nbsp};$ $\&\text{nbsp};\text{bronchitis},\text{ emphysema},\text{ irritation in the eyes},\text{ etc}.\&\text{nbsp};$ $\&\text{nbsp};\text{Nitrogen oxides are formed mainly from nitrogen and oxygen formed during the combustion of fossil fuels at high}\&\text{nbsp};$ $\&\text{nbsp};\text{temperatures in automobile engines}.\text{ Nitrogen oxides cause the reddish}-\text{brown haze in traffic congested city areas}.\&\text{nbsp};$ $\&\text{nbsp};\text{Both}\&\text{nbsp}; S O_{2} \&\text{nbsp};\text{and}\&\text{nbsp}; N O_{2} \&\text{nbsp};\text{contribute to the acid rain because they combine with the water droplets to produce nitric acid},\&\text{nbsp};$

Correct Answer: a

Explanation: N$_{2}$ Nitrogen gas is present in air up to 78% by volume. It does not cause pollution.

Correct Answer: c

Explanation: CO$_{2}$, CH$_{4}$, N$_{2}$O, O$_{3}$ CO$_{2}$, CH$_{4}$, N$_{2}$O, O$_{3}$ are green house gases. These gases absorb IR radiations and keep the surface of earth warm.