$t_{1/4}$ for a first-order reaction is given as:

Half-life of a first order reaction is $20 \ s$ and initial concentration of reactant is $0.2 \ M$. The concentration of reactant left after $80 \ s$ is (in $M$)

The reaction $A + B \xrightarrow{k}$ product is first order with respect to $A$ and zero order with respect to $B$. If $a_0$ and $a_t$ are the concentrations of $A$ at $t = 0$ and after time $t \, sec$ respectively,then select the correct relationship -

For a first order reaction,the concentration of reactant was reduced from $0.03 \ mol \ L^{-1}$ to $0.02 \ mol \ L^{-1}$ in $25 \ min$. What is its rate (in $mol \ L^{-1} \ s^{-1}$)?

Half life of a first order reaction is $20 \ min$. The time taken to reduce the initial concentration of reactant to $(1/10)^{th}$ is $\qquad$ (in $min$)

Catalytic decomposition of hydrogen peroxide is a ........ order reaction.