Give the definition of the following terms:
$(i)$ Rate of Reaction
$(ii)$ Average rate of reaction
$(iii)$ Instantaneous rate

(N/A) $(i)$ Rate of Reaction: The change in concentration of any one of the reactants or products per unit time is called the rate of reaction.
$(ii)$ Average rate of reaction: The rate of reaction measured over a definite time interval $( \Delta t )$ is called the average rate of reaction. It is given by $r_{av} = -\frac{\Delta [R]}{\Delta t} = +\frac{\Delta [P]}{\Delta t}$.
$(iii)$ Instantaneous rate: The rate of reaction at a particular instant of time is called the instantaneous rate. It is determined by calculating the slope of the tangent to the concentration-time graph at that specific time $t$,given by $r_{inst} = -\frac{d[R]}{dt} = +\frac{d[P]}{dt}$ as $\Delta t \to 0$.