Board-style MCQs and past-paper numericals in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved questions are at the bottom.
Multiple-choice questions
Solved numericals & self-assessment (past papers)
EMF of a Zn–Ag cell
E°(Zn²⁺/Zn) = −0.76 V, E°(Ag⁺/Ag) = +0.80 V. Ag is the cathode (higher E°).
E°cell = E°cathode − E°anode = (+0.80) − (−0.76) = +1.56 V
Oxidation number of Mn in KMnO₄
K = +1, O = −2 (×4 = −8), overall charge 0.
+1 + Mn − 8 = 0 → Mn = +7
Charge passed in electrolysis
A current of 2 A flows for 30 minutes. Find the charge.
Q = I × t = 2 × (30 × 60) = 2 × 1800 = 3600 C
Moles of electrons from a given charge
How many moles of electrons are in 96 500 C? (1 F = 96 500 C)
moles of e⁻ = 96 500 / 96 500 = 1 mole
Identify anode and cathode in the Daniell cell
Zn (E° = −0.76) is more easily oxidised → anode (−); Cu (E° = +0.34) is reduced → cathode (+).
Electrons flow Zn → Cu; E°cell = +1.10 V.