Question

Which of the following metal oxides is white in colour but becomes yellow on heating?

• A. $A{g}_{2}O$
• B. $ZnO$
• C. $FeO$
• D. $MgO$

Answer 1

The correct option is B $ZnO$

ZnO is white in colour.
Crystalline zinc oxide is thermochromic, changing from white to yellow when heated (doesn't decomposes) and in air reverting to white on cooling.