Answer:
D. It has a central nucleus composed of 35 protons and 45 neutrons,
surrounded by an electron cloud containing 35 electrons.
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Answer:
C. a rolling bowling ball
I just answered this question on my quiz.
Answer:
Velocity of the electron at the centre of the ring, 
Explanation:
<u>Given:</u>
- Linear charge density of the ring=

- Radius of the ring R=0.2 m
- Distance of point from the centre of the ring=x=0.2 m
Total charge of the ring

Potential due the ring at a distance x from the centre of the rings is given by

The potential difference when the electron moves from x=0.2 m to the centre of the ring is given by

Let
be the change in potential Energy given by

Change in Potential Energy of the electron will be equal to the change in kinetic Energy of the electron

So the electron will be moving with 
The Nucleus contains Protons and Neutrons.
The Neutrons does not have a charge.
The Protons are positively charge.
Hence the charge on the Nucleus, would be the charge of the proton, which is positive.
Hence Nucleus is Positively Charged.