$A$ blood-red colour is obtained when $Ferric$ $Chloride$ solution reacts with

$PCl_5$ reacts with finely divided silver on heating and a white silver salt is obtained,which dissolves on adding excess aqueous $NH_3$ solution. Write the reactions involved to explain what happens.

Iron salt used in blue prints is:

Match the metal in column $I$ with the coordination compounds/enzymes in column $II$.

Column $I$ (Metals)	Column $II$ (Coordination compounds)
$a. Co$	$i. \text{Wilkinson catalyst}$
$b. Zn$	$ii. \text{Chlorophyll}$
$c. Rh$	$iii. \text{Vitamin } B_{12}$
$d. Mg$	$iv. \text{Carbonic anhydrase}$

The compound used in the treatment of lead poisoning is

The colour of tetrammine copper$(II)$ sulphate is