When a copper wire is immersed in a solution of AgNO₃, the colour of the solution becomes blue because copper:

1. Forms a soluble complex with \(AgNO_3\)
2. Is oxidised to \(Cu^{2+}\)
3. Is reduced to \(Cu^{2-}\)
4. Splits up into atomic form and dissolves

If an iron rod is dipped in CuSO₄ solution, then:

1. Blue colour of the solution turns red.

2. Brown layer is deposited on iron rod.

3. No change occurs in the colour of the solution.

4. None of the above.

Without losing it's concentration, ZnCl₂ solution cannot be kept in contact with :

1. Au

2. Al

3. Pb

4. Ag

A gas X at 1 atm is bubbled through a solution containing a mixture of 1MY^- and 1MZ^- at 25$°$C. If the reduction potential of Z > Y > X, then:

1. Y will oxidise X and not Z

2. Y will oxidise Z and not X

3. Y will oxidise both X and Z

4. Y will reduce both X and Z

A solution containing one mole per litre each of Cu(NO₃)₂, AgNO₃, Hg₂(NO₃)₂ and Mg(NO₃)₂ is being electrolyzed by using inert electrodes. The values of standard electrode potentials in volt (reduction potentials) are,

Ag⁺ /Ag = 0.80 V, ${\mathrm{Hg}}_2^{2+}$/2Hg = 0.79 V,

Cu²⁺/Cu = +0.34 V and Mg²⁺/Mg = -2.37 V

With increasing voltage, the sequence of deposition of metals on the cathode will be:

1. Ag, Hg, Cu, Mg

2. Mg, Cu, Hg, Ag

3. Ag, Hg, Cu

4. Cu, Hg, Ag

Each of the three metals X, Y and Z were put in turn into aqueous solution of the other two.

X + Salt of Y (or Z) ⟶  Y (or Z) + Salt of X.

Which observation is probably incorrect?

1. Y + Salt of X = No action observed

2. Y + Salt of Z = Z + Salt of Y

3. Z + Salt of X = X + Salt of Z

4. Z + Salt of Y = No action observed

$2{\stackrel{\oplus }{\mathrm{Ag}}}_{\left(\mathrm{aq}\right)} + {\mathrm{Cu}}_{\left(\mathrm{s}\right)} \stackrel{ }{\rightleftharpoons } {{\mathrm{Cu}}_{\left(\mathrm{aq}\right)}}^{+2} + 2{\mathrm{Ag}}_{\left(\mathrm{s}\right)}$

The cell potential for this reaction is 0.46V. Which of the following change will increase the potential the most ?

(1) $\left[\stackrel{\oplus }{\mathrm{Ag}}\right]$ concentration is doubled

(2) [Cu²⁺] concentration is halved

(3) Size of Cu_(s) electrode is doubled

(4) size of Ag_(s) electrode is decreased to half

Which of the following is an incorrect statement :- 

1. Mercury cell is a primary cell providing a constant potential

2. During recharging lead storage cell works as electrolytic cell

3. Galvanised iron does not rust

4. In electrolytic cell reduction occurs at anode and in galvanic cell oxidation takes place at anode

Select the incorrect statement for dry cell

(1) Mn is reduced from Mn⁺⁴ to Mn⁺³

(2) NH₃ gas libreted out

(3) Zn is used as anode

(4) Paste of NH₄Cl and ZnCl₂ is used

Assertion : In electrochemical cell, we cannot use $\mathrm{KCI}$ in the salt bridge if anodic or cathodic

                  compartment consists of ${\mathrm{Ag}}^{+}$ of ${\mathrm{Pb}}^{2+}$ ion.

Reason : Salt bridge is employed to maintain the electrical neutrality and to minimize the liquid-liquid

               junction potential.