The Chemical Acidity of a Solution Is Measured in Units $\mathrm { pH } = - \log \left[ \mathrm { H } ^ { + } \right]$

Multiple Choice

The chemical acidity of a solution is measured in units of pH: $\mathrm { pH } = - \log \left[ \mathrm { H } ^ { + } \right]$ , where $\left[ \mathrm { H } ^ { + } \right]$ is the hydrogen ion concentration in the solution.If a sample of rain has a pH of 3.4, how many times higher is its $\left[ \mathrm { H } ^ { + } \right]$ than pure water's, which has a pH of 7?

A) $4.0 \times 10 ^ { 3 }$
B) $2.5 \times 10 ^ { 4 }$
C) 7
D) $2.5 \times 10 ^ { 3 }$
E) $4.0 \times 10 ^ { 4 }$