Which of the following compounds shows yellow appearance on heating and becomes white when cooled after…
Which of the following compounds shows yellow appearance on heating and becomes white when cooled after heating?
$\mathrm{CuCO}_{3}$
$\mathrm{PbO}_{2}$
$\mathrm{Pb}\left(\mathrm{NO}_{3}ight)_{2}$
$\mathrm{ZnCO}_{3}$
Solution
Zinc salts on heating appear yellow and become white on cooling that is why $\mathrm{Z_{n}} \mathrm{CO}_{3}$ (containing $\mathrm{Zn}^{2+}$) turns yellow when heated and white when cooled.