A Substance Has a Hydrogen Ion Concentration Of $\left[ \mathrm { H } ^ { \cdot } \right] = 3.7 \times 10 ^ { - 6 }$

Multiple Choice

A substance has a hydrogen ion concentration of $\left[ \mathrm { H } ^ { \cdot } \right] = 3.7 \times 10 ^ { - 6 }$ M. Find the pH of the substance.

A) $2.1$
B) $4.6$
C) $5.4$
D) $7.6$
E) $9.4$ ?