Given:

Charge on polythene piece = -3 × 10⁷ C

(a) Number of electrons transferred from wool to plastic.

Explanation: We know that all materials are electrically neutral. As per the question, after rubbing the polythene piece is found to be negatively charged which suggests that negatively charged particles i.e. electrons were transferred from wool to plastic.

Let number of electrons transferred from wool to plastic be ‘n’

From quantization of charges we know that

q = n × e …(1)

Where, q is the total charge

e = charge of individual particle

n = number of charges (either positive or negative)

e = -1.6 × 10^-19 C

From equation (1) we get,

q = n × e

⇒ n = q/e

⇒

⇒ n = 1.87 × 10¹²

The number of electrons transferred is 1.8 × 10¹²

(b) Yes, mass is transferred because each electron has a mass of 9.1 × 10^-31 Kg.

Mass transferred = n × m_e …(1)

Where, n = number of electrons

M_e = mass of electron (9.1 × 10^-31Kg)

Now, putting the values of M_e and n in equation (1).

⇒ M = 1.87 × 10¹² × 9.1 × 10^-31Kg

⇒ M = 1.706 × 10^-18 Kg

Hence, the mass transferred from wool to plastic is 1.7 × 10^-18 Kg