Answer: D
Key thing to keep note, is "refraction"...
Look at some experiments on YouTube, it's helps me a lot.
I think it's 1.03412969 or 1.03
Answer:
f = 1.354*10^{20} Hz
Explanation:
By conservation of linear momentum, wavelength shift due to collision of photon to electron is given by following formula

where h is plank constant = 6.626*10^{-34}
c = speed of light = 3*10^{8} m/s
scattered angle = 60 degree
m = rest mass of electron = 9*10^{-31}


we know that 1 pm = 10^{-12}m


f = 1.354*10^{20} Hz
let's convert 400 newtons to Kg, which is 40.7886.
now we put it in a formula that includes gravity and acceleration
(40.7886 kg) ( 9.8 m/s2) + (40.7886 kg) (0)
now we come up with the answer of 399.72828 kg or 3920 Newtons
Not sure which unit you are looking for but they are both there.