Answer:
2.11eV
Explanation:
We know that speed of light is it's wavelength times frequency.

Planck's constant is 
The energy gap is calculated by multyplying the light's frequency by planck's constant:

Hence, the energy gap is 2.11eV
The best option is C. This is due to friction.
Frost will disturb the smooth flow of air over the wing, unpleasantly
distressing its lifting competence. In other words, this spoils the even flow
of air over the wings, by this means decreasing lifting capability. Also, frost
may avoid the airplane from becoming flying at normal departure speed.