Answer:
D. A nucleus of 2 protons and 2 neutrons.
Explanation:
A stable nucleus is one that do not disintegrate naturally, majorly due to the even number of its protons and neutrons. Thus they are not radioactive in nature.
From the given question, it would be observed that a nucleus of 2 protons and 2 neutrons would give a helium atom. And this is a stable atoms due to the magnetic number of the components of its nucleus.
Thus, the nuclear configuration that is most stable out of the given options is a nucleus of 2 protons and 2 neutrons. Option D.
Answer:2.45 m/s
Explanation:
Given
Launch velocity
launch angle
as the vertical velocity first decreasing to zero and then increases to original value so its avg is zero .
thus 
Answer:
If you use the bicycle as a reference frame, your dog will appear to be moving backwards farther from you/your bicycle. Although the dog is sitting on one place, your bicycle is moving away from the dog
Explanation:
Because when liquids are cooled the molecules slow down and that causes liquids to freeze
