$A_1: C_6H_5CH_2Cl$
$A_2: C_6H_5CH_2OH$
$A_3: C_6H_5CHO$
$A_4: C_6H_5COONH_4$
PTHH:
$C_6H_5CH_3+Cl_2\xrightarrow{{as}} C_6H_5CH_2Cl+HCl$
$C_6H_5CH_2Cl+NaOH\xrightarrow{{t^o}}C_6H_5CH_2OH+NaCl$
$C_6H_5CH_2OH+CuO\xrightarrow{{t^o}} C_6H_5CHO+Cu+H_2O$
$C_6H_5CHO+2[Ag(NH_3)_2]OH\to C_6H_5COONH_4+2Ag+3NH_3+H_2O$