$$Cu$$ being more reactive than $$Ag$$ due to lower electrode potential, displaces $$Ag$$ from $$AgN{O_3}$$ solution. It is dissolved in the solution in the form of $$C{u^{2 + }}$$ ions.
164.
In the reaction shown below, oxidation state of the carbon in reactant and product are (i) and (ii) respectively? Is the given reaction a redox reaction?
$$N{a_2}C{O_3}\left( {aq} \right) + HCl\left( {aq} \right) \to $$ $$N{a^ + }\left( {aq} \right) + C{l^ - }\left( {aq} \right) + {H_2}O\left( l \right) + C{O_2}\left( g \right)$$
The redox reaction involve loss or gain of electron$$(s)$$ i.e. change in oxidation state.
Given reaction is not a redox reaction as this reaction involves no change in oxidation state of reactant or product.
165.
Which of the following is the strongest oxidizing agent?
$$P{b_3}{O_4}$$ is a mixture of $$PbO$$ and $$Pb{O_2}.$$
$$P{b_3}{O_4} \equiv 2PbO \cdot Pb{O_2} + 8HCl$$ $$ \to 3PbC{l_2} + C{l_2} + 4{H_2}O$$
In the reaction one $$P{b^{4 + }}$$ ion is reduced to $$P{b^{2 + }}$$ and two $$P{b^{2 + }}$$ ions remain unchanged.
167.
When $$KMn{O_4}$$ is reduced with oxalic acid in acidic solution, the oxidation number of $$Mn$$ changes from
(A) Neutralisation reaction
(B) $$3{O_2} \to 2{O_3},$$ allotropic formation
(C) $${N_2} + {O_2} \to 2NO$$
$${N_2}$$ is reduced and $${O_2}$$ is oxidised.
(D) In evaporation of $${H_2}O,$$ state changes only.
169.
The number of electrons involved in the conversion of $$MnO_4^ - $$ to $$Mn{O_2}$$ is
$$MnO_4^ - \to Mn{O_2}$$
Oxidation number of $$MnO_4^ - :x - 8 = - 1 \Rightarrow x = + 7$$
Oxidation number of $$Mn{O_2}:x - 4 = 0 \Rightarrow x = + 4$$
Change in oxidation number = 3
170.
For decolourisation of $$1\,mole$$ of acidified $$KMn{O_4}$$ the moles of $${H_2}{O_2}$$ required are