Define conductance and conductivity.
Or.
Define electrical conductivity of a conductor and give its S.I. unit.

Explanation

### Step-by-Step Solution

1. **Definition of Conductance**:
- Conductance is defined as the reciprocal of resistance. If \( R \) is the resistance of a conductor, then the conductance \( G \) is given by the formula:
\[ G = \frac{1}{R} \]
- The unit of conductance is denoted by \( G \), and its SI unit is Ohm inverse (Ω⁻¹).
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