Question
Why does a new aluminium vessel lose shine so soon after use?
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| Column I | Column II |
| (1) Ethyne | (a) $\mathrm{C}_2 \mathrm{H}_6$ |
| (2) Ethene | (b) $\mathrm{C}_2 \mathrm{H}_2$ |
| (3) Ethane | (c) $\mathrm{C}_3 \mathrm{H}_6$ |
| (4) Propyne | (d) $\mathrm{C}_2 \mathrm{H}_4$ |
| (e) $\mathrm{C}_3 \mathrm{H}_4$ |

| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of $-CH_2-$ units | Boiling point $^\circ C$ |
| Methane | $CH_4$ | $CH_4$ | $1$ | $1$ | $-162$ |
| Ethane | $C_2H_6$ | $CH_3–CH_3$ | $2$ | $2$ | $-88.5$ |
| Propane | $C_3H_8$ | $CH_3–CH_2–CH_3$ | $3$ | $3$ | $-42$ |
| Butane | $C_4H_{10}$ | $CH_3–CH_2–CH_2–CH_3$ | ______ | ______ | $0$ |
| Pentane | $C_5H_{12}$ | $CH_3–CH_2–CH_2–CH_2–CH_3$ | ______ | ______ | $36$ |
| Hexane | $C_6H_{14}$ | $CH_3–CH_2–CH_2–CH_2–CH_2–CH_3$ | ______ | ______ | $69$ |
| I | II | III |
| Coal | Potential energy | Wind electricity plant |
| Uranium | Kinetic energy | Hydroelectric plant |
| Water reservoir | Nuclear energy | Thermal plant |
| Wind | Thermal energy | Nuclear power plant |