Answer:
The order of maximum is 
Explanation:
From the question we are told that
The diffraction grating is k = 300 lines per mm = 300000 lines per m
The wavelength is 
Generally the condition for constructive interference is mathematically represented as

Here n is the order maximum
d is the distance the grating which is mathematically represented as

=> 
=>
So

at maximum 

=>
=> 
When galaxies move farther away the wavelength of the light is longer causing the galaxy to shift red but if it moves closer, the wavelength of the light gets smaller causing the galaxy to blue shift. The reason that the wavelength increases or decrease is due to the doppler effect.
I'm pretty sure that you put incorrect temperature number, since the number of temperature that you currently given does not make any sense.
Insert your correct temperature in this equation :
Ek = (3/2)kT
Hope this helped you out
uhm i think i don’t understand what it says but i can answer if it was English ! i also tried to translate it but it didn’t help !
For numbers 1 and 3 it is giving you the answers i believe
number 1 would be 20 joules of potential energy on the far left and far right point
number 3 would the (3rd) point as it says it has 20 joules of kinetic energy
sorry if this doesn’t help