Answer:

Given:
Charge on the body = -0.2 μC
Number of protons = 2.25 × 10^12

Concept:
An atom has the same number of electrons as protons. The charge on an electron is negative and the charge on a proton is positive. When the body is negatively charged, it means there are more electrons than protons. So, we need to calculate the number of extra electrons.

Calculation:
The charge on an electron is 1.6 × 10^-19 C.
Thus, the charge on 1 electron = -1.6 × 10^-19 C.

We can find the number of electrons by dividing the total charge by the charge on 1 electron.

Number of electrons = Total charge / Charge on 1 electron
Number of electrons = (-0.2 × 10^-6 C) / (-1.6 × 10^-19 C)
Number of electrons = 1.25 × 10^12

Therefore, the number of electrons in the body is 1.25 × 10^12.

Explanation:
In an atom, the number of protons in the nucleus is equal to the number of electrons in the shells outside the nucleus. The charge on an electron is negative and the charge on a proton is positive. In a neutral atom, the number of protons is equal to the number of electrons, so the positive charge of the protons is balanced by the negative charge of the electrons, making the total charge zero.

However, when the body is negatively charged, it means that there are more electrons than protons. The charge on an electron is known, so we can calculate the number of electrons by dividing the total charge by the charge on 1 electron. This gives us the number of extra electrons present in the body, which is equal to the number of protons plus the number of extra electrons. Therefore, by subtracting the number of protons from the total number of electrons, we get the number of extra electrons. This calculation helps us to find the number of electrons present in the body.