Neutrons do not carry an electrical charge so adding or removing them from the nucleus does not change the electrical charge of the nucleus. ... So, adding or removing protons from the nucleus changes what element that atom is! For example, adding a proton to the nucleus of an atom of hydrogen creates an atom of helium.
Cuz Of Newton’s third law, every actions there is an equal and opposite reaction.
Answer:
c.
=0 and 
Explanation:
We are given that two particles collide and stick together.
If there is no external force act on the two particles then ,it is inelastic collision.
Inelastic collision: There is some loss of kinetic energy but the momentum is conserved.
According to law of conservation of momentum
Initial momentum=Final momentum
Change in momentum=Final momentum-Initial momentum=0
Change in momentum=
Initial kinetic energy is greater than final kinetic energy.
Change in kinetic energy=Final kinetic energy-kinetic energy=- negative

Hence, option c is true.
c.
=0 and 
Velocity = displacement / time
v = 400 / 2
v = 200 km/h
In short, Your Answer would be 200 km/h
Hope this helps!
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