Take the relative reactivities per hydrogen for Cl2 at 25 degC as primary : secondary : tertiary = 1 : 3.8 : 5. The alkane shown is monochlorinated at 25 degC. What percentage of the product mixture is the tertiary chloride (to the nearest whole number)?

JEE Main levelSingle correct optionDifficulty 2 of 3o2251

Take the relative reactivities per hydrogen for $Cl X_{2}$ at 25 $^{\circ}$ C as primary : secondary : tertiary = 1 : 3.8 : 5. The alkane shown is monochlorinated at 25 $^{\circ}$ C. What percentage of the product mixture is the tertiary chloride (to the nearest whole number)?

The alkane is 2-methylpropane. Relative amounts are proportional to number of H times reactivity: primary

9 \times 1 = 9

, tertiary

1 \times 5 = 5

. The tertiary chloride is

5/14 = 35.7%

, about 36%, so 2-chloro-2-methylpropane is the minor product.