ANSWER Since 1.0 × 10 -7 has two significant figures, the pH can be reported as 7.00. A logarithmic scale condenses the range of acidity to numbers that are easy to use. Consider a solution with [H + ] = 1.0 × 10 -4 M. That is a hydrogen-ion concentration that is 1000 times higher than the concentration in pure water.
The answer is the: Kalvin Scale.
