Time required for $100\%$ completion of a zero order reaction is

Decomposition of $X$ exhibits a rate constant of $0.05 \ \mu g/year$. How many years are required for the decomposition of $5 \ \mu g$ of $X$ into $2.5 \ \mu g$?

In the following reaction $A \to B + C$,the rate constant is $0.001 \, M/sec$. If we start with $1 \, M$ of $A$,the concentrations of $A$ and $B$ after $10$ minutes are respectively:

$5$ 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 $10^{-X}\,moles/minute$. $[K_f(H_2O) = 1.86\, K\, Kg\,mol^{-1}]$

What is the unit of $K$ for a zero-order reaction?

For a reaction,doubling the concentration of the reactant doubles the half-life period. What is the order of the reaction?