If an object is charged by rubbing it against any other object, its mass
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → may increase or decrease slightly
Charging by rubbing (charging by friction) does not create charge; it only transfers electrons from one body to the other.
The body that gains electrons becomes negatively charged and its mass increases by the mass of the extra electrons; the body that loses electrons becomes positively charged and its mass decreases by the same amount.
\( m_{e} = 9.1\times10^{-31}\,\mathrm{kg} \text{ per electron} \)
Since the electron mass is so small, the change is only slight. The question does not say which kind of charge the object acquires, so its mass may increase or decrease slightly.
Why the other options are incorrect
Option (1) increases slightly — Incorrect. This is true only if the object becomes negatively charged (gains electrons).
Option (2) decreases slightly — Incorrect. This is true only if the object becomes positively charged (loses electrons).
Option (4) remains precisely the same — Incorrect. Electrons, which have mass, are transferred, so the mass cannot stay precisely the same, even though the change is tiny.