Solution

(a) ● Physiorption - (i) Not specific (ii) Low ΔH_adsorption
● Chemisorption- (i) Highly specific (ii) High ΔH_adsorption
(b) In adsorption, the substance is concentrated only at the surface while in absorption, the substance is uniformly distributed throughout the bulk of the solid / adsorption is a surface phenomenon while absorption is a bulk phenomenon

Solution

(a) It converts Ni into its volatile compound, Ni(CO)₄.

(b) It provides flux to remove impurities.

(c) It selectively prevents one of the sulphide ore from coming to the froth.

Solution

Solution

(a) t-butyl alcohol will undergo acid catalysed dehydration faster because the tertiary carbonium ion formed with t-butyl alcohol is more stable than primary carborium ion formed with n-butanol.
(b) img alt=src=" style=height:641px; width:500px
img alt=src=style=height:205px; width:350px
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Solution

(a) Zn (s) + Cu²⁺ (aq) —>Zn²⁺ (aq) + Cu (s).
Given : E° for Zn²⁺/Zn= E°ᵃⁿᵒᵈᵉ = – 0·76 V and
E° for Cu²⁺/Cu = E°ᶜᵃᵗʰᵒᵈᵉ = +0·34 V
(a) E°cell =E°c– E°a
= 0.34 – (-0.76)
= 1.10V
𝚫G°= -nFE°
= -2 × 1.10 × 96500
= -212300 J/mol or -212.3 kJ/mol

Advantage : -(1) A fuel cell works with an efficiency of 70 %.
(2) These are no objectionable by-products and therefore, its a pollution free source of energy.
or

(a) (i) Silver wire at 30°C because as temperature decreases, resistance decreases so conduction increases.
(ii) 0.1 M CH₃COOH, because on dilution degree of ionization increases hence conduction increases.
(iii) KCl solution at 50°C, because at high temperature mobility of ions increases and hence conductance increases.

● Electrochemical cell
(1) Anode -ve
Cathode +ve
(2) Convert chemical Energy to electrical energy.
● Electrolytic cell
(1) Anode +ve
Cathode -ve
(2) Convert electrical Energy to chemical energy.

Solution

(a) (i) Cu⁺¹(3d¹⁰) compounds are white because of absence of unpaired electrons while Cu⁺²(3d⁹) compounds are coloured due to unpaired e- which shows d-d transition.

(ii) Chromates (CrO₄²⁻) in the acidic solution are converted into dichromates and thus the colour becomes (Cr₂O₇²⁻) orange.

(iii) Transition elements are characterized by partially filled (n-1) d subshells. Zn, Cd and Hg are not regarded as transition elements as they have completely filled (n-1)d subshell. They possess completely filled d-orbitals in their ground state as well as in oxidized state.

(b) Co = [Ar]4s²3d⁷
Co⁺² =[Ar] 3d⁷
<p><img alt="" src="" style="height:184px; width:300px" /></p>

or
Lanthanoids
(1) Most of them are not radioactive.
(2) Don’t show a wide range of oxidation state.
(3) Most of their ions are colourless.
Actinoids
(1) All are radioactive.
(2) Show a wide range of oxidation states.
(3) Most of their ions are coloured.

(b) (i) Sc³⁺, because of absence of unpaired electron it is diamagnetic.
Sc= 1s² 2s² 2p⁶ 3s³ 3p⁶ 3d¹ 4s²
Sc³⁺= 1s² 2s² 2p⁶ 3s³ 3p⁶

(ii) Cr, because of presence of greater number of unpaired electrons leading to strong intermetallic bonding than Cu it has high melting and boiling point.
<p><img alt="" src="" style="height:207px; width:300px" /></p>