red light has wavelength 750nm whereas violet light has wavelength 400nm.

Calculate therir frequncy and energy.

(c=3x10⁸ms^-1, h=6.63x10^-34

Formula used to calculate frequency is ν = c/λ 

For red light given λ = 750nm = 7.5 ×10 -7 m  and c= 3× 10⁸ms^-1.Putting the value of λ and c in formula

 ν = c/λ we get 3× 10⁸ms^-1/7.5 ×10 -7 m = 4.0 × 10¹⁴s^-1.

energy can be calculated by using formula E= hν  = 6.63 × 10^-34Js  × 4.0 × 10¹⁴s^-1. = 2.65 × 10^-20J

similarly for violet light, ν = c/λ , 3× 10⁸ms^-1/4.0 ×10 -7 m = 7.5 × 10¹⁴s^-1

E= hν  = 6.63 × 10^-34Js  × 7.5 × 10¹⁴s^-1. = 4.97 × 10^-20J