Gaseous ${\mathrm{N}}_2{\mathrm{O}}_5$ decomposes according to the following equation: 

${\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)\to 2{\mathrm{NO}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)$

The experimental rate law is $-\mathrm{\Delta }\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]/\mathrm{\Delta t}=\mathrm{k}\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]$. At a certain temperature the rate constant is $\mathrm{k}=5.0\times {10}^{-4}{\sec }^{-1}$. In how many seconds will the concentration of ${\mathrm{N}}_2{\mathrm{O}}_5$ decrease to one-tenth of its initial value?