Question

Write down the changes that will be seen in the instance and explain the reason behind them. 

A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.

Answer 1

When litmus paper is dipped into 2 mL of dilute HCl solution, then blue litmus paper is turned into red colour and there is no effect on red litmus paper. Again, if the same litmus paper is dipped into 2 mL of concentrated NaOH solution, then red litmus paper turns into a blue colour but there is no effect on blue litmus paper. This is due to the respective properties of blue and red litmus paper with acid and base.