What is meant by the 'rate constant, k' of a reaction ? If the concentration be expressed in mol `L^(-1)` units and time in seconds, what would be the units for k (i) for a zero order reaction and (ii) for a first order reaction?

Explanation

### Step-by-Step Solution

1. **Definition of Rate Constant (k)**:
The rate constant (k) of a reaction is a proportionality constant that relates the rate of a chemical reaction to the concentration of the reactants. It indicates how fast a reaction occurs and is dependent on the order of the reaction and the temperature.

2. **Units of Concentration and Time**:
In this problem, the concentration is expressed in moles per liter (mol L^(-1)) and time is expressed in seconds (s).

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