What does the pH of a solution signify? Three solutions A, B and C have pH values of 6, 4 and 10 respectively. Which of the solutions is highly acidic? (b) A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical materials which he can mix with the soil to adjust its pH.

(a) pH is potential of hydrogen and signifies whether the solution is acid or base and also its strength. pH greater than 7 is considered as basic and lesser than 7 can be considered as acid. For neutral solutions pH will be 7.

Solution B with lower pH value of 4 is highly acidic

(b) Soil with pH 4.2 is acidic. It can be treated with the chemicals such as calcium oxide or calcium hydroxide which are bases and commonly called quick lime and slaked lime.