Question

A solution M turns blue litmus red, so it must contain _____ ions; another solution O turns red litmus blue and hence, must contain ________ions.

Answer 1

Acidic solution turns blue litmus red. Hence, there is presence of hydronium ion i.e $H_3{O}^{+}$ in solution M. Basic solution turns red litmus blue. Hence, there is presence of hydroxide ion i.e $O{H}^{-}$ in solution O.