The hydrogen concentration [ $\displaystyle{H}+\usepackage{cmbright}\Huge\$ ] of tomato juice is about $\displaystyle{1}\times{{10}}^{{-{{4}}}}\usepackage{cmbright}\Huge\$ . Use the formula $\displaystyle{p}{H}=-{\log{{\left[{H}+\right]}}}\usepackage{cmbright}\Huge\$ to find the approximate pH level of tomato juice.

$\displaystyle{p}{H}=\usepackage{cmbright}\Huge\$ _____