K.E = 1/2 mv²
800 = 1/2 ×12 ×v²
800 = 6 v²
800 / 6 = v²
= 133.4 =v²
√133.4 = √v²
11.5 = v²
I hope this answer is correct.
Answer:
162.78 m/s is the most probable speed of a helium atom.
Explanation:
The most probable speed:

= Boltzmann’s constant =
T = temperature of the gas
m = mass of the gas particle.
Given, m = 
T = 6.4 K
Substituting all the given values :


162.78 m/s is the most probable speed of a helium atom.
Machines makes work easier by increasing the amount of force that is applied, and changing the direction in which the force is applied !! Hope it helped (p.s. I had this same question)
Answer:
if im not mistaken i think its d let me know if correct plz