GATE2020: 38

A U-tube manometer contains two manometric fluids of densities $1000 \: kg \: m^{-3}$ and $600 \: kg \: m^{-3}$. When both the limbs are open to atmosphere, the difference between the two levels is $10 \: cm$ at equilibrium, as shown in the figure.

The rest of the manometer is filled with air of negligible density. The acceleration due to gravity is $9.81 \: m \: s^{-2}$ and the atmospheric pressure is $100 \: kPa$. How much absolute pressure (in $kPa$) has to be applied on the limb $’P’$ to raise the fluid in the limb $’Q’$ by another $20 \: cm$?

1. $100.175$
2. $103.924$
3. $547.231$
4. $833.206$

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