Chemistry

This is a short answer type question as classified in NCERT Exemplar

H₂O₂ decomposes slowly on exposure to light.

2H₂O₂→ 2H₂O+2O₂

In daily life it is used as a hair bleach and as a mild disinfectant. As an antiseptic it is sold in the market as perhydrol.

This is a short answer type question as classified in NCERT Exemplar

(i) Oxidising action in acidic medium:

2Fe²⁺ (aq)+2H⁺ (aq)+H₂O₂ (aq) → 2Fe³⁺ (aq)+2H₂O (l)

PbS (s)+4H₂O₂ (aq) → PbSO₄ (s)+4H₂O (l)

(ii) Reducing action in acidic medium:

2MnO₄^-+6H⁺+5H₂O₂ → 2Mn²⁺+8H₂O+5O₂

HOCl+H₂O₂ → H₃O⁺+Cl^-+H₂O

This is a short answer type question as classified in NCERT Exemplar

H₂O₂ structure in gas phase, dihedral angle is 111.50. H₂O₂ structure in solid phase at 110 k, dihedral angle is 90.20.

This is a short answer type question as classified in NCERT Exemplar

Heavy water can be used as a moderator in nuclear reactors and in exchange reactions for the study of reaction mechanisms. It can be prepared by exhaustive electrolysis of water or as a by-product in some fertilizer industries.

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Hydrogen economy (Hydrogen as fuel):

(i) The electricity cannot be stored in automobiles. It is not possible to store and transport nuclear energy. Hydrogen is an alternative source of energy and hence called the 'hydrogen economy". Hydrogen has some advantages as fuel.

(ii) Available in abundance in combined form as water.

(iii) On combustion produces H₂O. Hence, pollution free.

(iv) H₂O₂ fuel cells give more power.

(v) Excellent reducing agent. Therefore, it can be used as a substitute of carbon in reduction for processes in industry.

This is a short answer type question as classified in NCERT Exemplar\

In sodium the last shell electron is in 3s₁ after losing that electron, it can acquire the configuration of Ne. Whereas in hydrogen, the electron is in s-orbital.

This is a short answer type question as classified in NCERT Exemplar

Because of ionization enthalpy, hydrogen resembles more with halogens, is 520 kJ mol^-1, F is 1680 kJ mol^-1and that of His 1312 kJ mol^-1. Like halogens, it forms a diatomic molecule, combining with elements to form hydrides and a large number of covalent compounds.

This is a Long Answer Type Questions as classified in NCERT Exemplar

The equation can be written as-

A^p+_x  +  B^q- _y ? xA^p+ (aq) +  yB^q-

S moles of A and B dissolves to give x S moles of A^p+ and y S moles of Bq-.

K_sp = [A^p+]^x   [B^q-]^y = [x5]^x [y5]^y

= x^x y ^y 5 ^x+y

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans: option (iv) 

If the volume is kept constant and an inert gas such as argon is added which does not take part in the reaction, the equilibrium remains undisturbed.

This is a Assertion and Reason Type Questions as classified in NCERT Exemplar

Ans:  option (iii)

Salt of weak acid and weak base can form buffer solution.