In a first-order reaction A $$ \to $$ B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is

If 60% of a first order reaction was completed in 60 minutes, 50% of the same reaction would be completed in approximately
(log 4 = 0.60, log 5 = 0.69)

For the reaction, 2A + B $$ \to $$ 3C + D, which of the following does not express the reaction rate?

Consider the reaction :  N_2(g) + 3H_2(g) $$ \to $$ 2NH_3(g)

The equality relationship between $${{d\left[ {N{H_3}} \right]} \over {dt}}$$ and $$ - {{d\left[ {{H_2}} \right]} \over {dt}}$$ is