Chapter 20, Problem 35QAP

. Indicate the missing molecule in each of the following substitution reactions.

a. ${\text{CH}}_4+{\text{Cl}}_2\stackrel{hv}{\to }\text{HCL}+?$   b. ${\text{CH}}_{\text{2}}{\text{Cl}}_{\text{2}}+{\text{Cl}}_{\text{2}}\stackrel{hv}{\to }{\text{CHCI}}_{\text{3}}+?$   c. $?+{\text{Cl}}_{\text{2}}\stackrel{hv}{\to }{\text{CCl}}_{\text{4}}+\text{HCI}$   d. ${\text{CH}}_3\text{CI}+?\stackrel{hv}{\to }{\text{CH}}_{\text{2}}{\text{Cl}}_{\text{2}}+\text{HCI}$