The difference in height between the columns of a manometer is $200 \mathrm{~mm}$, with a fluid of density 900 $\mathrm{kg} / \mathrm{m}^{3}$. What is the pressure difference? What is the height difference if the same pressure difference is measured using mercury (density $\left.=13600 \mathrm{~kg} / \mathrm{m}^{3}\right)$ as manometer fluid?