A gas mixture contains $6$ moles of H$2$ and $2$ moles of N$2.$ If the total pressure of the gaseous mixture is $4$ kgf$/$cm$2$; then the partial pressure of N$2$ in the mixture will be $\_\_\_\_\_\_\_\_\_$ kgf$/$cm$2.$

$1$

$2$

$4$

$8$