(S)-1-Chloro-2-methylbutane undergoes light-induced reaction with $\mathrm{Cl}_{2}$ by a radical mechanism to yield a mixture of products. Among the products are 1,4 -dichloro-2methylbutane and 1,2 -dichloro-2-methylbutane.
(a) Write the reaction, showing the correct stereochemistry of the reactant.
(b) One of the two products is optically active, but the other is optically inactive. Which is which?
(c) What can you conclude about the stereochemistry of radical chlorination reactions?