Question

A metal was burnt in air. The Substance formed was dissolved in water and tested with blue and red litmus paper. What result do you expect?

Answer 1

$\mathrm{M}+{\mathrm{O}}_2\to {\mathrm{MO}}_2$

When a metal is burnt in the air, it gets oxidized in the presence of oxygen and forms metal oxide. The metal oxide is basic in nature, so it produced a basic solution when dissolved in water. Hence, in the basic solution, blue litmus paper will not change its colour whereas the red litmus will turn blue.