Question

A solution has a [H+] of 0.20 M. Find the pH of this solution.

Answer 1

The pH of this solution : 0.699

Further explanation  

pH is the degree of acidity of a solution that depends on the concentration of H⁺ ions. The greater the value the more acidic the solution and the smaller the pH.  

pH = - log [H⁺]  

So that the two quantities between pH and [H⁺] are inversely proportional because they are associated with negative values.  

A solution whose value is different by n has a difference in the concentration of H⁺ ion of 10ⁿ.  

A solution has a [H+] of 0.20 M, so [H⁺]=0.2

$\tt pH=-log[H^+]\\\\pH=-log[0.2]\\\\pH=1-log~2\\\\pH=0.699$