In zero order, rate is independent of Concentration of reactants

Rate $=\mathrm{K}$

In first order, half life $\left({\mathrm{t}}_{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\right)$ is dependent only on $\mathrm{K}$

${\mathrm{t}}_{\raisebox{1ex}{${}_1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}=\frac{0.693}{\mathrm{K}}$

So no change with respect to concentration.