Chemistry · Oct / Nov 2025 · Paper 12 · Question 22

Elements P, Q, R and S are in either Group I or Group VII of the Periodic Table. P is a liquid at r.t.p. Q is a gas at r.t.p. Elements R and S both form basic oxides. Element R has a higher melting point than element S. Which pair of elements gives the most vigorous reaction?

1. AP and R
2. BP and S
3. CQ and R
4. DQ and S

As printed in the paper