In a solution the concentration of hydrogen ion is 1 x 10-7 moles/litre at 25degC. The pH of the solution will be:
High-Yield Explanation
The term pH is defined as the negative log of the hydrogen ion concentration; that is, For the given solution at 25degC, Low pH values correspond to high concentrations of H+ and high pH values correspond to low concentrations of H+. Ref: Kennelly P.J., Rodwell V.W. (2011). Chapter 2. Water & pH. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.