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CBSE 12th Standard Chemistry Subject The p-Block Elements HOT Questions 3 Mark Questions With Solution 2021

Published on: 28/05/2021

QB365 Provides the HOT Question Papers for Class 12 Chemistry, and also provide the detail solution for each and every HOT Questions. HOT Questions will help to get more idea about question pattern in every exams and also will help to get more marks in Exams

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Std: 12th Standard CBSE - Chemistry

chapter: - HOT Questions

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Questions:

Generic 3

2 x 3 = 6

A colourless inorganic salt-(A) decomposes completely at 25⁰ C to give only two products (B), and (C) leaving no residue. The product (C) is a liquid at room temperature and neutral to moist litmus paper while the gas (B) is a neutral oxide. White phosphorus burns in excess of (B) to produce a strong white dehydrating agent. Write balanced equations for the reactions involved in the above process.

Why is \({ SO }_{ 2 }\) a better reducing agent in alkaline medium as compared to that in acidic medium? Explain?

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Answers Key:

Generic 3

2 x 3 = 6

This data indicates that the compound 'A' is NH₄NO₃ and it reacts as follows:
\(NH_{ 4 }NO_{ 3 }\overset { 25°C }{ \longrightarrow } \underset { (B) }{ N_{ 2 }O } +\underset { (C) }{ 2H_{ 2 }O } \)
(Neutral to litmus)
\(P_{ 4 }+10N_{ 2 }O\overset { heat }{ \longrightarrow } P_{ 4 }O_{ 10 }+10N_{ 2 }\)
(Dehydrating agent)

\({ SO }_{ 2 }\) acts as a reducing agent because of the liberation of nascent hydrogen in the presence of moisture:
\({ SO }_{ 2 }+2{ H }_{ 2 }O\rightleftharpoons { H }_{ 2 }{ SO }_{ 4 }+{ 2H }\)
Alkali neutralises the acid and shifts the equilibrium in the forward direction producing more nascent hydrogen. However, in acidic medium, the equilibrium is suppressed resulting in a lesser amount of nascent hydrogen. Consequently, \({ SO }_{ 2 }\) is better reducing agent in alkaline medium than in the acidic medium.