Question

Which of the following oxides can dissolve in water to form a solution that would turn litmus indicator red in colour?

• A. $MgO$
• B. $K_{2}O$
• C. ${CO}_2$
• D. $ZnO$
• E. $H_{2}O$

Answer 1

The correct option is C ${CO}_2$

Litmus paper is used to test whether the given solution is acidic or alkaline in nature. Litmus paper is a natural indicator. Indicators are red in acids and blue in bases. In other words, acids change blue litmus paper to red; bases change red litmus paper to blue. $MgO,K_{2}O$ and $ZnO$ are basic oxides while $C{O}_2$ is the acidic oxide.

So, the given acidic oxide of carbon, i.e., carbon dioxide turns blue litmus red.