n – Butane is treated with chlorine at ${25}^0\mathrm{C}.$ The percentage of 1-Chlorobutane formed is (x – 0.2) x 10. The x is

At room temp, the relative rates of abstraction of hydrogenations are 5 : 3.8 : 1

                $\frac{\text{1}\text{-}\text{chlorobutane}}{\text{2}\text{-}\text{chlorobutane}}\text{=}\frac{\text{No}\text{.}{\text{of1}}^{\text{0}}\text{-}\text{H}}{\text{No}\text{.}\text{of}{\text{2}}^{\text{0}}\text{-H}}\text{x}\frac{\text{reactivity}\text{of}{\text{1}}^{\text{0}}\text{H}}{\text{reactivity}\text{of}{\text{2}}^{\text{0}}\text{H}}\text{=}\frac{\text{6}}{\text{4}}\text{x}\frac{\text{1}}{\text{3}\text{.8}}\text{=}\frac{\text{6}}{\text{15}\text{.2}}$

% of 1 – chlorobutane = $\frac{\text{6}}{\text{21}\text{.2}}\text{x}\text{100}\text{=}\text{28}\text{.3}\text{\%}$

[x – 0.2] 10 = [3 – 0.2] 10 = 28 % [nearly]