JAMB Physics 2023 Paper

Concept:In an open-tube manometer, the gas tank pressure equals atmospheric pressure plus the hydrostatic pressure due to the mercury column.Explanation:The mercury column is $25\,\text{cm} = 0.25\,\text{m}$ higher on the open side.Since the open tube is higher, the tank pressure is greater than atmospheric pressure.Use the formula:$$P_{\text{abs}} = P_{\text{atm}} + \rho g h$$Substitute the given values:$$P_{\text{abs}} = 101{,}325 + (13600)(9.8)(0.25)$$Calculate the hydrostatic pressure:$$13600 \times 9.8 \times 0.25 = 33{,}320\,\text{Pa}$$Add to atmospheric pressure:$$P_{\text{abs}} = 101{,}325 + 33{,}320 = 134{,}645\,\text{Pa}$$Answer:The absolute pressure in the tank is $134{,}645\,\text{Pa}$, which is option D.