Answer:
Momentum Packet Answer KEY - Science Online
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The answer is having fewer neutrons than protons or electrons.
Answer:

Explanation:
When we push the box from the bottom of the incline towards the top then by work energy theorem we can say that
Work done by all the forces = change in kinetic energy of the system

here we know that

also we know that the length of the incline is given as

now we have

so we have

Helium has only 2 electrons in it's valence shell
So, option D is your answer.
Hope this helps!