The mercury column in the barometer at notational  atmospheric pressure has a height of?

Analyze the question: The question asks for the height of the mercury column in a barometer at normal (standard) atmospheric pressure. "Notational" is a typo for "normal."

Concept: A mercury barometer balances the weight of the mercury column against atmospheric pressure. At sea level, standard atmospheric pressure is about 101,325 Pa (1 atm), and this supports a mercury column of 760 mm = 76 cm.

Solution: Use P = hρg.

• P = 101,325 Pa (about 1.013 × 10⁵ Pa)
• ρ (mercury) = 13,600 kg/m³
• g = 9.8 m/s²

h = P / (ρg) h = 101,325 / (13,600 × 9.8) h = 101,325 / 133,280 h ≈ 0.76 m = 76 cm

Checking the options:

• A. 0.76 cm: too small, it is 100 times too small.
• B. 760 cm: this mixes up mm and cm, because 760 is the value in mm.
• C. 7.6 cm: too small.
• D. 76 cm: correct.

Tip: Remember "760 mm = 76 cm = 0.76 m of mercury." JAMB often tests unit conversions by swapping mm, cm, and m among the options. Check the unit before you pick 760.