Manometer measures pressure difference via liquid column height

Steps:

• Convert height difference to meters: 72 mm = 0.072 m.
• Calculate pressure difference: ρgh = (13600 kg/m³)(10 N/kg)(0.072 m) = 9792 Pa = 9.792 kPa.
• Add to atmospheric pressure: gas pressure = 100 kPa + 9.792 kPa ≈ 101 kPa.
• Select closest option matching this value.

Why C is correct:

• Manometer gauge pressure is ρgh; absolute gas pressure is atmospheric pressure plus ρgh for supply above atmosphere.

Why the others are wrong:

• A: Equals atmospheric pressure, ignoring mercury column contribution.
• B: Subtracts ρgh from atmospheric, implying gas pressure below atmosphere.
• D: Unrelated doubling of atmospheric pressure, exceeding calculated value.

Final answer: C