The rates of a certain reaction $(dc/dt)$ at different times are as follows:

Time $(sec)$	Rate $(mole \ litre^{-1} \ sec^{-1})$
$0$	$2.8 \times 10^{-2}$
$10$	$2.78 \times 10^{-2}$
$20$	$2.81 \times 10^{-2}$
$30$	$2.79 \times 10^{-2}$

The reaction is:

$5$ milli-moles of a solid $A$ was dissolved in $5$ moles of $H_2O$. On adding to the solvent,$A$ starts polymerising into another insoluble solid following zero order kinetics. On adding $6$ milli-moles of another solid solute $C$ (after $20$ minutes) the polymerisation completely stops. The insoluble solid polymer is removed and the resulting solution was cooled to a temperature less than $-0.186\,^{\circ}C$ (melting point of solution) to cause solidification of some liquid water. Calculate the value of $'X'$ if rate constant for polymerisation reaction is represented as $10^{-X}\,moles/minute$. $[K_f(H_2O) = 1.86\, K\, Kg\,mol^{-1}]$

For the reaction $A \longrightarrow 3 B$,the rate is given by $rate = k[A]^0$. Based on the data provided in the table,what is the concentration of the product $B$ (in $mol \ L^{-1}$) after $20 \ s$?

Time $(s)$	Concentration of the reactant $(mol \ L^{-1})$
$0$	$0.1$
$15$	$0.05$
$20$	$0.1 - x$

The unit of velocity constant in case of zero order reaction is

For a zero-order reaction,the ratio of $t_{1/2}$ to $t_{3/4}$ is ....

What is the unit of rate constant for the zero order reaction?