Question

what happen when a solution of metal oxide is tested with blue Litmus Paper and red litmus paper

Answer 1

metal oxides are basic in nature
hence when tested with blue litmus paper it remains blue but when tested with red litmus paper it turns red

hope it helps

Answer 2

Metal oxides are generally basic in nature.

When metal oxides react with acid they form respective metal salt and water.

Acid + Metal Oxide => Salt + Water

Neutralization Reaction :

Acid + Base => Salt + Water

This is similar to neutralization reaction where base comes instead of Metal oxide. Hence it can be concluded that Metal oxide is a base.

So Bases generally turn Red litmus to blue.

Hence the solution of any metal oxide will turn Red litmus to Blue but it has no effect on the Blue Litmus paper.