Chemistry Class 11 NCERT Solutions: Chapter 8 Redox Reactions Part 8 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 13. Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions:

(A)

(B)

(C)

(D)

(E)

Answer:

(A) Oxidised substance ⇾

Reduced substance ⇾

Oxidising agent ⇾

Reducing agent ⇾

Q_13_A_Structure of Silver Bromide

(B) Oxidised substance ⇾

Reduced substance ⇾

Oxidising agent ⇾

Reducing agent ⇾ HCHO

(C) Oxidised substance ⇾

Reduced substance ⇾

Oxidising agent ⇾

Reducing agent ⇾

(D) Oxidised substance ⇾

Reduced substance ⇾

Oxidising agent ⇾

Reducing agent ⇾

(E) Oxidised substance ⇾

Reduced substance ⇾

Oxidising agent ⇾

Reducing agent ⇾

Q: 14. Consider the reactions:

Why does the same reductant, thiosulphate react differently with iodine and bromine?

Answer

The average oxidation number (O. N.) of S in is + 2. Being a stronger oxidising agent than oxidised , in which the O. N. of S is + 6. However, is a weak oxidising agent. Therefore, it oxidised in which the average O. N of S is only + 2.5. As a result, reacts differently with iodine and bromine.

Q: 15. Justify giving reactions that among halogens, fluorine is the best oxidant and among

a Hydrohalic compound, hydroiodic acid is the best reductant.

Answer

as:

On the other hand, , and cannot oxidize . The oxidizing power of halogens increases in the order of . Hence, fluorine is the best oxidant among halogens.

HI and can reduce , but HCl and HF cannot. Therefore, HI and HBr are

stronger reductants than HCl and HF.

Again, I – can reduce cannot.

Hence, hydroiodic acid is the best reductant among hydrohalic compounds.

Thus, the reducing power of hydrohalic acids increases in the order of

Q: 16. Why does the following reaction occur?

What conclusion about the compound (of which is a part) can be drawn

from the reaction.

Answer:

The given reaction occurs because oxidises reduces

In this reaction, the oxidation number (O. N.) of decreases from + 8 in to + 6 in

and the O. N. of F increases from – 1 in F – to O in .

Hence, we can conclude that is a stronger oxidising agent than

Q: 17. Consider the reactions:

(A)

(C)

(D) ⇾ No change observed.

What inference do you draw about the behaviour of and from these reactions?

Answer:

and act as oxidising agents in reactions

(A) And

(B) Respectively. In reaction

(C) oxidises to but in reaction

(D) cannot oxidise C6H5CHO.

Hence, we can say that is a stronger oxidising agent than .

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