A few drops of fruit juice are put on the pH paper and it turns red in colour. The possible pH of the juice is-

A pH scale is a concept used to express the hydrogen ion concentration in a solution.

$\mathrm{pH} = -\log \left[{\mathrm{H}}^{+}\right]$

The pH range from 0 to 14. '0' represents a very acidic solution and '14' represents a very basic solution.

7 is the pH of a neutral solution.

Now, on the pH paper, the colour red represents a highly acidic solution. Thus, the pH of the juice is less than 3.

Hence, The possible pH of the juice is <3.