Question

The rate of a reaction at a particular instant of time is called:

• A. Instantaneous rate
• B. Average rate
• C. Non-spontaneous rate
• D. Spontaneous rate

Answer 1

The correct option is A Instantaneous rate

Instantaneous rate of a reaction:
Rate of reaction at a particular instant is called Instantaneous rate of a reaction.
For a reaction
$A⟶B$
$R_{\text{instantaneous}}=\underset{\Delta t\to 0}{lim}\left(\frac{\Delta C}{\Delta t}\right)=\frac{dC}{dt}$
In terms of reactant A:
$R_{\text{instantaneous}}=-\frac{d\left[A\right]}{dt}$
Negative sign indicates decrease in the reactant's concentration.

In terms of product B:
$R_{\text{instantaneous}}=\frac{d\left[B\right]}{dt}$