$[\mathrm{CO}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}] \mathrm{Cl}_{2} \stackrel{\mathrm{AgNO}_{3}}{\longrightarrow} 2\, \mathrm{mol}\; \mathrm{AgCl}$
$\left[\mathrm{CO}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}\stackrel{\mathrm{AgNO}_{3}}{\longrightarrow} 1\, \mathrm{mol}\; \mathrm{AgCl}$
$(A)$ $\left. Na _{4}\left[ Fe ( CN )_{5} NOS \right)\right]$
$(B)$ $Na _{4}\left[ FeO _{4}\right]$
$(C)$ $\left[ Fe _{2}( CO )_{9}\right]$