(a) How is pH paper used to find the pH of a solution?
(b) The pH value of water is 7. What will be the pH value of (i) aqueous solution of sodium hydroxide and (ii) dil. HCl.

Explanation

(a) With the help of a dropper one drop of the solution a placed on the strip of the pH paper. The colour developed on the pH paper is compared with the colour and the corresponding pH value given on the chart of the pH paper.
(b) aqueous solution of sodiium hydroxide is alkaline so its pH will be more than 7.
dil HCl is acidic so its pH value will be less than 7.