Correct. Substitute the value $\displaystyle{1}\times{{10}}^{{-{{4}}}}\usepackage{cmbright}\Huge\$ for [ $\displaystyle{H}+\usepackage{cmbright}\Huge\$ ] in the formula and simplify.

$\displaystyle{p}{H}=-{\log{{\left[{1}\times{{10}}^{{-{{4}}}}\right]}}}=-{{\log{{10}}}}^{{-{{4}}}}\usepackage{cmbright}\Huge\$

Use the power property to simplify: $\displaystyle{p}{H}={\left(-{4}\right)}{\left(-{\log{{10}}}\right)}\usepackage{cmbright}\Huge\$

$\displaystyle{\log{{10}}}={1}\usepackage{cmbright}\Huge\$ , so the $\displaystyle{p}{H}={\left(-{4}\right)}\cdot{\left(-{1}\right)}={4}\usepackage{cmbright}\Huge\$ .