Blue litmus is added to two test tubes A and B containing dilute HCl and NaOH. Answer respectively. In which test tube a colour change will be observed? State the colour change and give its reason.
Test tube A contains dil. HCl and test tube B contains dil. NaOH. On adding blue litmus Answer to both the test tubes, the colour of the test tube A will change from blue to red. This is because HCl is acid and acids turn blue litmus to red.