Class 11 Chemistry - Chapter Redox Reactions NCERT Solutions | Suggest a list of the substances where c

Balance the following redox reactions by ion – electron method :

(a) MnO₄ ^– (aq) + I ^– (aq) → MnO_{2 (s)} + I_2(s) (in basic medium)

(b) MnO₄ ^– (aq) + SO_{2 (g)} → Mn²⁺ (aq) + HSO₄^– (aq) (in acidic solution)

(c) H₂O_{2 (aq)} + Fe ²⁺ (aq) → Fe³⁺ (aq) + H₂O (l) (in acidic solution)

(d) Cr₂O₇ ^2– + SO_2(g) → Cr³⁺ _(aq) + SO₄^2– (aq) (in acidic solution)

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH₂PO₄

(b) NaHSO₄

(c) H₄P₂O₇

(d) K₂MnO₄

(e) CaO₂

(f) NaBH₄

(g) H₂S₂O₇

(h) KAl(SO₄)₂.12 H₂O

What are the oxidation number of the underlined elements in each of the following and how do you rationalise your results ?

(a) KI₃

(b) H₂S₄O₆

(c) Fe₃O₄

(d) CH₃CH₂OH

(e) CH₃COOH

Justify that the following reactions are redox reactions:

(a) CuO_(s) + H_2(g) → Cu_(s) + H₂O_(g)

(b) Fe₂O_3(s) + 3CO_(g) → 2Fe_(s) + 3CO_2(g)

(c) 4BCl_3(g) + 3LiAlH_4(s) → 2B₂H_6(g) + 3LiCl_(s) + 3 AlCl_{3 (s)}

(d) 2K_(s) + F_2(g) → 2K⁺F^– _(s)

(e) 4 NH_3(g) + 5 O_2(g) → 4NO_(g) + 6H₂O_(g)

Balance the following equations in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the reducing agent.

(a) P_4(s) + OH ^– _(aq)  →  PH_3(g) + HPO^{2 –} _(aq)

(b) N₂H_4(l) + ClO^{3 –} _(aq)  →  NO_(g)  +  Cl^–_(g)

(c) Cl₂O_{7 (g)}  +  H₂O_2(aq)  →  ClO ^– _2(aq)   +  O_2(g)  +  H ⁺ _(aq)

Fluorine reacts with ice and results in the change:

H₂O_(s) + F_2(g) → HF_(g) + HOF_(g)

Justify that this reaction is a redox reaction.

Write the formulae for the following compounds:
(a) Mercury(II) chloride
(b) Nickel(II) sulphate
(c) Tin(IV) oxide
(d) Thallium(I) sulphate
(e) Iron(III) sulphate
(f) Chromium(III) oxide

While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why?

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

(a) 2AgBr _(s) + C₆H₆O_2(aq) → 2Ag_(s) + 2HBr _(aq) + C₆H₄O_2(aq)

(b) HCHO_(l) + 2[Ag (NH₃)₂]⁺_(aq) + 3OH^-_(aq) → 2Ag_(s) + HCOO^-_(aq) + 4NH_3(aq) + 2H₂O_(l)

(c) HCHO _(l) + 2Cu²⁺_(aq) + 5 OH^-_(aq) → Cu₂O_(s) + HCOO^-_(aq) + 3H₂O_(l)

(d) N₂H_4(l) + 2H₂O_2(l) → N_2(g) + 4H₂O_(l)

(e) Pb_(s) + PbO_2(s) + 2H₂SO_4(aq) → 2PbSO_4(s) + 2H₂O_(l)

The compound AgF₂ is an unstable compound. However, if formed, the compound acts as a very strong oxidizing agent. Why?

How do you account for the formation of ethane during chlorination of methane?

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

What are the common physical and chemical features of alkali metals?

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

What is the basic theme of organisation in the periodic table?

Explain the formation of a chemical bond.

Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Write Lewis dot symbols for atoms of the following elements: Mg, Na, B, O, N, Br.

Compare the structures of H₂O and H₂O₂.

Explain, giving reasons, which of the following sets of quantum numbers are not possible.

a n = 0 l = 0 ml = 0  

b n = 1 l = 0 ml = 0  

c n = 1 l = 1 ml = 0   

d n = 2 l = 1 ml = 0  

e n = 3 l = 3 ml = – 3

f n = 3 l = 1 ml = 0 

Name a suitable technique of separation of the components from a mixture of calcium sulphate and camphor.

How much time would it take to distribute one Avogadro number of wheat grains, if 10¹⁰ grains are distributed each second?

Which hybrid orbitals are used by carbon atoms in the following molecules?

(a)CH₃–CH₃;

(b) CH₃–CH=CH₂;

(c) CH₃-CH₂-OH;

(d) CH₃-CHO

(e) CH₃COOH

Explain the significance of sodium, potassium, magnesium and calcium inbiological fluids.

What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15, 19, 23 and 44 with dihydrogen? Compare their behaviour towards water.

For the following equilibrium, K_c = 6.3 × 10¹⁴  at 1000 K

NO (g) + O₃ (g) ↔ NO₂ (g) + O₂ (g)

Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is K_c, for the reverse reaction?

What do you understand by the terms:

(i) hydrogen economy

(ii) hydrogenation

(iii) 'syngas'

(iv) water-gas shift reaction

(v) fuel-cell ?