Chemical Kinetics · Arrhenius equation and activation energy

$\ce{A -> B}$ (first reaction)

$\ce{C -> D}$ (second reaction)

Consider the above two first-order reactions. The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 hour. The activation energy of the second reaction is half of that of first reaction. If the rate constant at 500 K of the second reaction becomes double of the rate constant of first reaction at the same temperature; then rate constant for the second reaction at 300 K is $\times 10^{-1}$ hour$^{-1}$ (nearest integer).