Answer:
732.9 mmHg
Step-by-step explanation:
At the eudiometer tube is the mixture of water and hydrogen gas (H₂), by Dalton's law of the partial pressure, the total pressure of a gas mixture (barometric pressure) is equal to the sum of the partial pressures of the components of the mixture:
Ptotal = Pwater + Phydrogen
752.3 = 19.4 + Phydrogen
Phydrogen = 752.3 - 19.4
Phydrogen = 732.9 mmHg