Molecules made up solely of non-metal atoms are covalently bonded. The formulae of four covalently bonded molecules are listed below: 1 nitrogen, $\text{N}_2$; 2 carbon dioxide, $\text{CO}_2$; 3 ethene, $\text{C}_2\text{H}_4$; 4 methanol, $\text{CH}_3\text{OH}$. Which of these molecules has double bonds?
- A1 and 4
- B2 and 3
- C2 and 4
- D4 only