Blue Litmus solution is added to two test tubes A and B containing dilute HCl and NaOH solution respectively. in which test tube a color change will be observed? state the color change and give its reason.

Hint: In the given question change in the medium of solution has been discussed when a solution is added in its color change which shows the type of solution. As the Litmus is a mixture of different dyes extracted from lichens which is water-soluble.

Complete step-by-step answer:
Acid-base chemistry plays a significant role in chemistry and in day to day life because every chemical reaction can be classified as an acid-base reaction. We know that HCl is a strong acid and NaOH is a strong base.
So, when we add blue litmus solution in both test tubes following changes takes place-in test tube A in which dilute HCl acid is present the H+ ion concentration increases when it is added to a solution which leads to the decrease in the pH value of the solution in the test tube. Already we know that Acids have the tendency to change blue litmus to red. Whereas in test tube B no color change will take place it will be blue only because in it already NaOH base is present, therefore no color change will occur in test tube B.
Hence, in test tube A the color will change as, it is an acid so, blue litmus turns to red

Note: Note that if a solution has higher concentration of H+ ions it is known to be more acidic in nature and when concentration has lower concentration it is known as basic in nature. When the sample is adsorbed onto litmus paper it produces one of the oldest forms of pH indicator that is used to test materials for acidity.