Question

Aqueous solution of a metal oxide changes the colour of litmus paper from _____ to ____.

• A. red, blue
• B. blue, red
• C. red, red
• D. red, pink

Answer 1

Answer: (A)

red, blue

Metal Oxides are basic in nature because they react with dilute acids to form salt and water. they also dissolve in water to form Metal hydroxides which are Alkaline in nature. These metal hydroxides release $O{H}^{-}$ ions, so they are basic.

When the solution of metal oxide is tested for the litmus paper test then it will turn the red litmus paper to blue because of its basic nature. When the solution of non-metallic oxide is treated with litmus paper then it will turn blue litmus paper to red.