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` .

Explanation

a. False : Br radical being less reactive is less influenced by the probability factor. The bromination primarily depends on the reactivity of H atom which is `3^(@) gt 2^(@) gt 1^(@)`.
b. False : The chlorination of propane gives two isomeric products ---- 1 - chloroporpane and 2-chloro-propane. Their relative ratio would be gives as:
`(1-"Chloropropane")/(2-"Chloropropane") = ("No. of " 1^(@) H)/("No. of " 2^(@) H) xx ("Reactivity of " 1^(@) H)/("Reactivity of " 2^(@) H)`
`= (6)/(2)xx(1.0)/(3.8)=(6.0)/(7.6)`
Percentage of `1^(@)` isomer `=(6.0)/(6.0 + 7.6)xx100 = 44%`
c. True : - Isobutane is
Its chlorination would give two isomers.
`(1^(@)"isomer")/(3^(@)"isomer") = ("No. of " 1^(@) H)/("No. of " 3^(@) H)xx("Reactivity of " 1^(@) H)/("Reactivity of " 3^(@) H)`
`= (9)/(1)xx(1)/(5.0) = (9)/(5)`
Percentage of `1^(@)` isomer `= (9)/(9 + 5)xx100 =64.3%`
d. False : The propane is `CH_(3)CH_(2)CH_(3)`. The relative ratio of the two isomers is
`1^(@) H = 6 H = 6xx1 = 6` , `2^(@) H = 2xx82 =164`
Total reactivity `=6 + 164 =170`
Percentage of `1^(@)` isomer `=(6)/(170)xx100 =3.52%`