Answer:
V = 0.356 L
Explanation:
In this case, we need to use the following expression:
M = n/V (1)
Where:
M: molarity of solution (mol/L or M)
n: moles of solute (moles)
V: Volume of solution (Liters)
From these expression, we can solve for V:
V = n/M (2)
Now, replacing the given data we can solve V:
V = 8.9 / 25
V = 0.356 L
Jupiter------------------------
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