If P=M*V than P=30kg*5m/s. P=150.
P=momentum
M=mass
V=Velocity
Now the last time i have done physics was last year. but i'm pretty confident in this answer. Hope this helps!
Answer : The chemical symbol for the element that results from this process is, (Ar) for argon.
Explanation :
Electron capture : In this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. Simply, a proton and an electron combines together to form a neutron. Mass number does not change in this process.

The equation for the given reaction is,

Thus, the chemical symbol for the element that results from this process is, argon (Ar).
1 mole ----------- 22.4 L ( at STP )
3.5 mols --------- ?
V = 3.5 x 22.4 / 1
V = 78.4 L
hope this helps!