A Substance Has a Hydrogen Ion Concentration Of $\left[ \mathrm { H } ^ { + } \right] = 4.0 \times 10 ^ { - 3 }$

Essay

A substance has a hydrogen ion concentration of $\left[ \mathrm { H } ^ { + } \right] = 4.0 \times 10 ^ { - 3 }$
M. Find the pH of the substance.