Ph Value

Correct answer: Blue litmus turns to red

Explanation:
Litmus paper is an indicator used to test whether a substance is acidic or basic.

When an acid is tested: - Blue litmus paper turns red, indicating the presence of an acid. - Red litmus paper remains red in acidic solutions.

Hence, the correct answer is: Blue litmus turns to red.

When a salt is formed from a weak acid and a strong base, the resulting solution is basic. This is because the strong base dissociates completely, and the conjugate base of the weak acid (present in the salt) hydrolyzes to form ions, making the solution basic. The pH of such a solution is typically greater than 7, as the concentration of ions will make the solution alkaline. In this case, the pH is approximately 9.

The correct option is (B): 9

Rainwater is naturally slightly acidic with a pH of about 5.6 due to dissolved carbon dioxide forming carbonic acid. If the pH of rainwater is lower than 5.6, it is considered acid rain, which can be caused by pollutants like sulfur dioxide and nitrogen oxides.
Thus, the correct answer is 5.6.