State whether each of the following is true or false.
a. Photobromination of 2-methylpropane gives a mixture of 1-bromo-2-methylpropane gives a mixture of 1-bromo-2-methylpropane and 2-bromo-2-methylpropa ne in the ratio `9 : 1`
b. The percentage of n-propyl chloride obtained in the chlorination of propane is about `56%`.
c. The percentage of 1-chloro-2-methylpropane obtained in the chlorination of isobutane is about `64%`.
d. The percentage of n-propyl bromide in the bromination of propane is `44%` . The relative reactives of `3^(@)` , `2^(@)` and `1^(@)` H atoms are `1600 : 82 : 1` .