Answer:
Option D, 1
Step-by-step explanation:
The pH of any substance range from 0 to 14.
Where Acidic substances have pH varying with in the range of 0 to 7
and Basic substances have pH varying with in the range of 7 to 14
and the pH of 7 represents a neutral substance.
The lower is the pH of a substance , the higher is the acidity.
Thus, both pH 1 and 5 represents the acidic substance but pH 1 represents a substance with higher acidity.
Hence, option D is correct.