The \(\mathrm{pH}\) of a substance measures its acidity or alkalinity. It is found by the formula \[p H=-\log \left[H^{+}ight]\] where \(\left[\mathrm{H}^{+}ight]\)is the concentration of hydrogen ions in an aqueous solution given in moles per liter. Find the \(\mathrm{pH}\) (to the nearest tenth) for the solutions in Problems 29-32.

lemon with \(\left[\mathrm{H}^{+}ight]=2.86 \times 10^{-4} \quad 3.5\)