Chemistry Past year IIT JEE question bank - Electrochemistry

1. Faraday’s laws of electrolysis are related to the

a. atomic number of the cation.
b. atomic number of the anion.
c. equivalent weight of the electrolyte
d. speed of the cation
(JEE 1983)

Ans: ©

2. A solution containing one mole for litre each of Cu(NO3)2, AgNO3, Hg2(NO3)2 and Mg(NO3)2 is electrolysed using inert electrodes. Standard electrode potentials in volts (reduction potentials) are:

Ag⁺| Ag = 0.80
Hg2²⁺ |Hg = 0.79
Cu²⁺|Cu = 0.34
Mg²⁺|Mg = -2.37

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

a. Ag,Hg,Cu, Mg
b. Mg,Cu,Hg,Ag
c. Ag,Hg, Cu
d. Cu,Hg, Ag

Ans: ( C )


3. The electric charge or electrode deposition of one gram equivalent of a substance is:

a. one ampere for one second
b. 96,500 coulombs per second
c. one ampere for one hour
d. charge on one mole of electrons
(JEE 1984)

ans (d)

4. The reaction ½ H2(g) + AgCl(s) = H⁺(aq) + Cl^-
(aq) +Ag(s) occurs in the galvanic cell:

a. Ag|AgCl(s) |KCl(soln) |AgNO3(soln) |Ag
b.Pt|H2(g) |HCl(soln) |AgNO3(soln) |Ag
c. Pt|H2(g) |HCl(soln) |AgCl(s) |Ag
d. Pt|H2(g) |KCl(soln) |AgCl(s) |Ag
(JEE 1985)

Ans: c
In cell c reactions occurring are

AgCl(s) + e^- -> Ag(s) + Cl^-(aq)
½ H2(g) -> H⁺ (aq) + e^-

adding ½ H2(g) + AgCl(s) = H⁺(aq) + Cl^-
(aq) +Ag(s)