Question

Which one of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torchlights, electric shaver etc. ? 

(a) Nickel and cadmium (b) Zinc and carbon (c) Lead peroxide and lead (d) Iron and cadmium

Answer 1

(a) Ni-Cd batteries contain nickel hydroxide as positive electrode plate, a cadmium hydroxide as negative electrode plate, and an alkaline electrolyte as seperator. The chemical reaction which occurs in Ni-Cd battery is 

2NiO(OH) + Cd + 2H₂O ↔ 2Ni(OH)₂ + Cd(OH)₂