Question

When galena is treated with ozone , the colour change occur from
A. black to red
B. red to white
C. black to white
D. white to black

Answer 1

Hint: Galena is also known as lead glance. It is the natural mineral form of lead (II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is Lead Sulphide (PbS). It is black in colour. Reaction of galena with ozone gives Lead Sulphate and oxygen.

Complete step by step answer:
Galena is basically Lead Sulfide (PbS).
Lead Sulfide (PbS) which is black in colour, reacts with ozone to produce oxygen and Lead Sulfate ($PbSO_4$) which is white in colour. The reaction takes place at normal room temperature.
$$PbS + 4{O_3} = PbS{O_4} + 4{O_2}$$
So when galena is treated with ozone , the colour change occurs from black to white.

So, the correct answer is Option C.

Note: Note that Lead Sulfide (PbS) reacts with ozone to produce oxygen and Lead Sulfate (PbSO4). The reaction takes place at normal room temperature.
$$PbS + 4{O_3} = PbS{O_4} + 4{O_2}$$