(i) Carbon isn't utilized for diminishing aluminum oxide since aluminum is more responsive than carbon. Thus, carbon can't uproot aluminum from its oxide. Aluminum oxide is exceptionally steady and Carbon is less responsive than aluminum, hence it can't be utilized to diminish aluminum oxide to aluminum metal.
(ii) An aqueous solution of sodium chloride is not used for electrolysis because aqueous solution contains water as well which results in the formation of sodium hydroxide in the solution and sodium metal is not obtained.
NaCl(aq) -Electricity- NaOH(aq) + H2(g)(at cathode) + Cl2(g)(at anode)
Hence molten sodium chloride is used to extract sodium from sodium chloride.
NaCl(l) -Electricity-Na(s)(at cathode) + Cl2(g)(at anode)
(iii) The reduction of a metal oxide to form metal by using aluminium powder as a reducing agent is called a thermite reaction. This reduction property of aluminium is used in thermite welding for joining the broken pieces of heavy iron objects like girders, railway tracks or cracked machine parts.

K = Ae^-Ea/RT
Ea, absence of catalyst = x KJ/mol
Ea, presence of catalyst = (x-20)KJ/mol
At 500K K = Ae-x/R.500
At 400
K = Ae-(x-20)/R.400
Divide 1 by 2, we get
X = 100KJ/mol
Ea = 100KJ/mol.

(i) The black powder acts as a catalyst. The catalysts accelerate the speed of reactions without itself undergoing any permanent changes
(ii) Black powder is manganese dioxide (Mn02).
(iii) Black powder cannot be used for all decomposition reactions because catalysts are highly specific in nature. A catalyst which can catalyse one reaction may have no effect on another reaction even, if that reaction is very similar.
(iv) Glycerol slows down the decomposition of H₂O₂ and it is called negative catalyst

\({ PtCl }_{ 4 }.2{ NH }_{ 3 }\)has the structural formula \(\left[ Pt{ \left( { NH }_{ 3 } \right) }_{ 2 }{ Cl }_{ 4 } \right] \)and\({ PtCl }_{ 4 }.2KCL\) has the structural formula \({ K }_{ 2 }\left[ { PtCl }_{ 6 } \right] \). In both cases, the Cl^- ions are present in the coordination sphere and are not ionizable. Therefore, these don't give tests for Cl^- ions with \({ AgNO }_{ 3 }\) solution.

It is given that
\(\underset { (X) }{ { C }_{ 6 }{ C }_{ 3 }CI } \overset { { ({ C }H_{ 3 }) }_{ 3 }COK }{ \longrightarrow } \ { \underset { (Y)\ and\ (Z) }{ Twoisomeric\\ alkenes\ of\ \\ formula\ { C }_{ 6 }{ H }_{ 12 }\ } }\overset { { H }_{ 2 } }{ \longrightarrow } \underset { 2,3-Dimethylbutance }{ { C }H_{ 3 }-\overset { \underset { | }{ { C }H_{ 3 } } }{ CH } -\overset { \underset { | }{ { C }H_{ 3 } } }{ CH } -{ C }H_{ 3 } } \)
The two alkenes forming 2, 3-dimethyl butane are:
\(\underset { (Y) }{ { C }H_{ 3 }-\overset { \underset { | }{ { C }H_{ 3 } } }{ C } =\overset { \underset { | }{ { C }H_{ 3 } } }{ C } -{ C }H_{ 3 } } \quad and\quad \underset { (Z) }{ { C }H_{ 2 }=\overset { \underset { | }{ { C }H_{ 3 } } }{ C } -\overset { \underset { | }{ { C }H_{ 3 } } }{ CH } -{ C }H_{ 3 } } \)

During leaching process, (Au) is first oxidised by \({ O }_{ 2 }\) of the air to \({ Au }^{ + }\)  which then combines with \({ CN }^{ - }\)  ions to form the soluble complex, dicyanoaurate (I) \(4Au(s)+8NaCN(aq)+{ O }_{ 2 }(g)+2{ H }_{ 2 }O(l)\longrightarrow 4Na[Au{ (CN) }_{ 2 }](aq)+4NaOH(aq)+\underset {Sodium dicyanoaurate(I)(Solublecomples) }{ 4NaOH(aq) } \)
Gold is then extracted from this complex by displacement method by using a more electropositive zinc metal. In this method, zinc acts as a reducing agent and it reduces \({ Au }^{ + }\) to Au. Zinc itself gets oxidised to \({ Zn }^{ 2+ }\) ions which combine with \({ CN }^{ - }\) ions to form soluble complex, sodium tetracyano zincate (II).
\(2Na[Au{ (CN) }_{ 2 }](aq)+Zn(s)\longrightarrow 2Au(s)+\underset { Sodium\quad tetracyano\quad zincate(II)(Soluble\quad comples) }{ { Na }_{ 2 }[Zn{ (CN })_{ 4 } } \) 
Thus, extraction of gold by leaching with NaCN involves both oxidation and reduction.

This statement is true. If vapour pressure of a liquid is high, lesser heating is needed to make its vapour pressure equal to the external  pressure (atmospheric pressure). Therefore, its boiling point is lower.