Answer: Total pressure inside of a vessel is 0.908 atm
Explanation:
According to Dalton's law, the total pressure is the sum of individual partial pressures. exerted by each gas alone.
= partial pressure of nitrogen = 0.256 atm
= partial pressure of helium = 203 mm Hg = 0.267 atm (760mmHg=1atm)
= partial pressure of hydrogen =39.0 kPa = 0.385 atm (1kPa=0.00987 atm)
Thus 
=0.256atm+0.267atm+0.385atm =0.908atm
Thus total pressure (in atm) inside of a vessel is 0.908
Henry's law constant for oxygen is 0,0013 mol/L·<span>atm. Air has 21,0% oxygen.
concentration of oxygen at 1 atm: 0,0013 mol/L</span>·atm · 0,21 · 1 atm = 0,000273 mol/l.
concentration of oxygen at 1 atm: 0,0013 mol/L·atm · 0,21 · 0,892 atm = 0,000243 mol/l.
difference in concentration: 0,000273 - 0,000243 = 0,00003 mol/L.
n(oxygen) = 0,00003 mol/L · 4,40 L = 0,000132 mol.
Sodium oxide + Water= Sodium hydroxide
