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

Answer: (C)

black to white

Lead(II) sulfide $PbS$ (Black) react with ozone to produce lead(II) sulfate $PbS{O}_4$ (White) and oxygen. The reaction occurs at at room temperature.

$PbS+4O_3\to PbS{O}_4+4O_2$

So when galena is treated with ozone ,the colour change occur from black to white.

Hence option C is correct.