c
\({\varphi _T} = \frac{Q}{{{\varepsilon _0}}}\). \({\varphi _{cube}} = \frac{Q}{{8{\varepsilon _0}}}.\) \( = \frac{1}{3} \times \left[ {\frac{1}{8}\left( {\frac{Q}{{{\varepsilon _0}}}} \right)} \right] = \frac{1}{{24}}\frac{Q}{{{\varepsilon _0}}}\).