The pH scale is a logarithmic scale that measures the concentration of hydrogen ions in a solution. A decrease in one unit of pH corresponds to a ten-fold increase in the concentration of hydrogen ions. Therefore, a solution of pH 4 has 10 times more hydrogen ions than a solution of pH 5.
To answer the question, we can calculate the ratio of hydrogen ion concentrations between the two solutions:
Ratio of hydrogen ion concentrations = 10^(pH5 - pH4) = 10^(5-4) = 10
Therefore, a solution of pH 4 is 10 times more acidic than a solution of pH 5.
The answer is B) 10.
~~~Harsha~~~