Which of the following pairs of metals are extracted only by electrolysis?

1. Na, Pb
2. Ca, Cu
3. Na, Mg
4. Ag, K

In the following reaction, alkaline KMnO₄ adds oxygen to the ethanol and converts ethanol to an acid.

CH₃CH₂OH $\xrightarrow{\text{KMnO}_4}$ CH₃COOH

Which of the following is correct?

P. Alkaline KMnO₄ acts as reducing agent.

Q. Alkaline KMnO₄ acts as an oxidising agent.

1. Only P
2. Only Q
3. Both P and Q
4. Neither P nor Q

On reaction of magnesium nitride with water, the gas which is liberated is ……………

1. NH₃
2. HCl
3. H₂
4. N₂

In an exothermic process, energy is released in the form of heat or light.

Which of the following could be exothermic processes?

P. Sublimation of camphor crystals

Q. Reaction of water with quick lime

R. Dilution of an acid

1. Only P
2. Only Q
3. Only R
4. Both Q and R