If we mix a pentavalent impurity in a crystal lattice of Ge, what type of semiconductor formation will occur?

• p-type

• n-type

• Both (a) and (b)

• None of these

If 'F' is Faraday and 'N' is Avogadro number, then charge of electron can be expressed as

• F × N

• $\frac{\mathrm{F}}{\mathrm{N}}$

• $\frac{\mathrm{N}}{\mathrm{F}}$

• F²N

By passing 9.65 A current for 16 min 40 s, the volume of O₂ liberated at STP will be

• 280mL

• 560mL

• 1120mL

• 2240mL

By diluting a weak electrolyte, specific conductivity (K_c) and equivalent conductivity (Λ_c) change as

• both increase

• K_c increase λ_c decrease

• K_c decrease λ_c increase

• both decrease

In Daniel cell, anode and cathode are respectively

• Zn| Zn²⁺ and  Cu²⁺|Cu 

• Cu²⁺|Cu and Zn| Zn²⁺

• Fe|Fe²⁺ and Cu²⁺|Cu

• Cu²⁺|Cu and Fe|Fe²⁺

Copper sulphate solution is electrolysed using copper electrode. The reaction taking place at anode is

• H⁺ + e^- → H

• SO${}_4^{2-}$ (aq) → SO₄ + 2e^-

• Cu²⁺ + 2e^- → Cu

• Cu (s) → Cu²⁺ (aq) + 2e-

How many cc of oxygen will be liberated by 2 A current flowing for 3 min 13 s through acidulated water?

• 11.2 cc

• 33.6 cc

• 44.8 cc

• 22.4 cc

Consider the following statements.
(1) Fuel cells are voltaic cell which convert electrical energy of fuel into chemical energy.

(2) Fuel cells are galvanic cells which convert chemical energy of fuel into electrical energy.

(3) The efficiency of H₂-O₂ fuel cell is approximately 25%.

(4) Fuel cells do not cause pollution problem.

Among these, the correct statements are

• (2) and (3) only

• (1) and (4) only

• (2) and (4) only

• (2), (3) and (4) only

The standard reduction potential E° for half-reactions are

Zn → Zn²⁺ + 2e^- ; E° = +0.76 V

Fe → Fe²⁺ + 2e^- ; E° = +0.41 V

The EMF of the cell reaction

Fe²⁺ + Zn → Zn²⁺ + Fe is

• +1.28 V

• -1.28 V

• +0.35 V

• -0.35 V

Certain electric current for half an hour can collect 11.2 L of hydrogen at NTP. Same current when passed through an electrolytic solution for one hour, can deposite how much silver?

• 216g

• 108 g

• 47 g

• 60 g