Helium has an atomic mass of 4.00 atomic mass units.
1)

Answer:
d. 12.25J
------------------------
2)
According to the conservation of energy:

Answer:
b. 12.25
-------------------------------
3)

Answer:
d. 0 kg∙m/s
-----------------------------------------
4)
Using conservation of momentum:

Answer:
b. 0 kg•m/s
There is NO planet that has a temperature even close to the Earth. The closest<span> would be Mars with a max of -5oC.</span>