Chemistry : PYQs with Answers

Maximum electrons in a shell = $2n^2$. For n = 3: $2 \times 3^2 = 18$.

At the cathode (negative electrode), reduction occurs: $2H^+ + 2e^- \rightarrow H_2$. So hydrogen is produced.

Sublimation is the direct conversion of solid to gas. Examples include dry ice (CO₂) and camphor.

Noble gases (He, Ne, Ar, Kr, Xe, Rn) are in Group 18 and are chemically inert due to complete electron shells.

Methane (CH₄) is the simplest hydrocarbon, containing just one carbon atom.

Magnesium loses electrons to oxygen, so it is oxidised. Oxygen is reduced. This is a redox reaction.