Answer: B. \(\text{N}_2\) has a triple bond (N≡N) — 3 shared pairs = 6 bonding electrons. \(\text{O}_2\) has a double bond (O=O) — 2 shared pairs = 4 bonding electrons. So more electrons are used to form the bonds in \(\text{N}_2\) than in \(\text{O}_2\). B is the only chemically true statement.
A is wrong despite hexane being a liquid and ethane a gas: the C–C and C–H covalent bonds in hexane and ethane have essentially the same strength. The higher boiling point of hexane comes from stronger intermolecular forces (more electrons → stronger dispersion forces), not stronger covalent bonds. The whole statement is therefore false because the reason it gives is wrong.
C is wrong: \(\text{SiO}_2\) is a giant covalent solid (m.p. ~1700 °C), not a gas. D is wrong: \(\text{CS}_2\) is a simple molecular compound — no mobile ions or electrons, so it conducts in neither state.
Every O Level Pure Chemistry TYS MCQ solution video, plus full Sec 3 / Sec 4 topic recordings.
Find out more