<h2>Hi there!</h2><h3>Sodium hydroxide is a base and turns red litmus blue.</h3>
Explanation:
If the substance is acidic, the blue litmus paper will turn red. Red litmus paper turns blue if the substance is basic or alkaline. Litmus turns red in acidic solutions and blue in simple solutions.
What is litmuspaper ?
Paper with a dye that turns red in the presence of acid and blue in the presence of a base.