The Gap between the valance band and the conduction band for Ge is 0.7 eV. Now we know 1eV=1.6*10^-19J. Thus, the energy gap in Germanium crystal is 0.7*1.6*10^-19 J = 1.12*10^-19 J.

If you are studying the Semiconductor Physics, then its always recommended that you should remember the Energy gap of Germanium and Silicon as this are most used materials in semi conductors.

For Si the energy gap is 1.14eV or 1.82*10^-19 J

I hope this answer helps. All the very best for your future endeavors!