Class 11 NEET Chemistry Hydrocarbons Questions

Concept:The reactions demonstrate free radical chlorination of alkanes and photochemical addition of chlorine to arenes.Chemical Equation / Formula:$CH_4 + 3Cl_2 \xrightarrow{\text{sunlight}} CHCl_3 + 3HCl$ (Product $X$ is chloroform)$C_6H_6 + 3Cl_2 \xrightarrow{\text{sunlight}} C_6H_6Cl_6$ (Product $Y$ is benzene hexachloride)Explanation:Methane undergoes stepwise substitution with excess chlorine in sunlight to form chloroform ($CHCl_3$), which contains three chlorine atoms.Benzene does not undergo substitution under UV light; instead, addition of three $Cl_2$ molecules occurs across the double bonds to form benzene hexachloride ($C_6H_6Cl_6$), which has six chlorine atoms.Thus the organic products $X$ and $Y$ carry 3 and 6 chlorine atoms respectively.Shortcut:Excess chlorination of methane stops at $CHCl_3$ or $CCl_4$ — here the product is $CHCl_3$ (3 Cl).Benzene + excess $Cl_2$ in sunlight always gives the hexachloro derivative (6 Cl).Answer:Option D: 3 and 6.