For the reaction. 2 HI ⟶ H2 + I2, the expression [ ] d HI dt represents

It indicates instantaneous rate of reaction as let us see option-wise. (a) Rate of formation of HI is not valid in this case as HI is being consumed. (b) Rate of disappearance of HI = d HI dt (c) The instantaneous rate is the rate at a particular time. 2 2 d HI d H d I 1 2 dt dt dt (d) The average rate is the change in concentration over a selected period of time. 2 2 HI H I 1 2 t t t