A white insecticide X is made by adding chlorine to benzene in sunlight, C6H6 + 3Cl2 -> C6H6Cl6. Using C 12, H 1 and Cl 35.5, the type of reaction at benzene and the mass percentage of chlorine in X are

electrophilic substitution; 73.2%

electrophilic substitution; 24.7%

JEE Advanced levelSingle correct optionDifficulty 3 of 3ev199

A white insecticide X is made by adding chlorine to benzene in sunlight, $C X_{6} H X_{6} + 3 Cl X_{2} C X_{6} H X_{6} Cl X_{6}$ . Using C 12, H 1 and Cl 35.5, the type of reaction at benzene and the mass percentage of chlorine in X are

Under UV light chlorine adds to benzene by a free-radical mechanism without a catalyst, and substitution is not involved. The molar mass of

C X_{6} H X_{6} Cl X_{6}

72 + 6 + 213 = 291

. Chlorine content is

213/291 = 73.2%

, while carbon is

72/291 = 24.7%