The decomposition of phosphine (PH₃) on tungsten at low pressure is a first-order reaction. It is because the

The rate of first-order reaction is 0.04 mol L^$$-$$1 s^$$-$$1 at 10 seconds and 0.03 mol L^$$-$$1 s^$$-$$1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is

The addition of a catalyst during a chemical reaction alters which of the following quantities?

The rate constant of the reaction A $$ \to $$ B is 0.6 $$ \times $$ 10^$$-$$3 mol L^$$-$$1 s^$$-$$1. If the concentration of A is 5 M, then concentration of B after 20 minutes is