Barometer: Atmospheric pressure equals ρgh, proportional to mercury height

Steps:

• Standard barometer reading: 0.76 m Hg corresponds to 0.1 MPa atmospheric pressure.
• The problem states this exact condition twice: pressure 0.1 MPa gives height 0.76 m.
• For the same height of 0.76 m, the pressure remains unchanged at 0.1 MPa.
• No other factors (e.g., temperature, gravity) are mentioned, so direct equivalence holds.

Why C is correct:

• Matches the given definition: 0.76 m Hg defines 0.1 MPa standard pressure by Torricelli's law.

Why the others are wrong:

• A: Too low; implies height ~0.19 m Hg, not 0.76 m.
• B: Too low; implies height ~0.57 m Hg, not 0.76 m.
• D: Too high; implies height ~0.99 m Hg, not 0.76 m.

Final answer: C