Atmospheric pressure from mercury barometer formula

Steps:

• Apply the barometer pressure formula: P = ρ g h, where ρ is mercury density, g is 9.8 m/s², and h is column height from diagram.
• Substitute ρ = 1.4 × 10³ kg/m³.
• From diagram, h = 0.0076 m (7.6 mm mercury column).
• Calculate P = (1.4 × 10³) × 9.8 × 0.0076 = 104 Pa.

Why C is correct:

• Matches P = ρ g h, the hydrostatic pressure law balancing atmospheric pressure on the mercury column.

Why the others are wrong:

• A: Underestimates by factor of ~26, likely from ignoring g or unit error in h.
• B: Overestimates by factor of ~200, possibly mistaking ρ for 10⁴ kg/m³.
• D: Overestimates by factor of ~1100, akin to standard mercury density (1.36 × 10⁴ kg/m³) with h = 0.76 m.

Final answer: C