A student chlorinates 2-methylbutane, (CH₃)₂CHCH₂CH₃, in a sealed glass flask at room temperature…

A student chlorinates 2-methylbutane, $(\text{CH}_{3})_{2}\text{CHCH}_{2}\text{CH}_{3}$, in a sealed glass flask at room temperature, with a lamp as the source of light. Chlorine is the limiting reagent, so that almost all the product is monochlorinated, and the mixture is analysed by gas chromatography. She wants to compare the percentages that she measures with values predicted from the number of hydrogen atoms of each kind and their relative reactivities. One primary, one secondary and one tertiary hydrogen atom have relative rates of $1.0$, $3.8$ and $5.0$ towards a chlorine atom under these conditions.

Give the four monochloro products, with their structures and names, and find the percentage of each. Give the answers to one decimal place. State which kind of hydrogen atom is replaced most easily, and which product is the largest in the mixture, and explain why they are not the same. She then repeats the experiment with bromine in place of chlorine and finds that one product is far larger than in the first experiment. Say which product that is likely to be, and why.