Answer: The mass of 
 liberated is 0.0383 g and the mass of NaH that reacted 0.455 g.
Explanation:
The given data is as follows.
        Volume = 0.501 L,
  Temperature of gas = 
 = (35 + 273) K = 308 K,
  Total pressure = 760 mm Hg
   Vapor pressure of water at 
 = 422 mm Hg
   Partial pressure of 
 = (760 - 422) mm Hg
                                      = 717.8 mm Hg
The chemical equation is as follows.
        
Using ideal gas equation, we will find the moles of hydrogen gas as follows.
              PV = nRT
          n = 
As we know,
                1 atm = 760 mm Hg
       717.8 mm Hg = 
     
                              = 0.944 atm
Putting the given values into the above formula we will calculate the number of moles as follows.
                     n = 
                        = 
                        = 0.0190 moles
Now, we will find the mass of 
 as follows.
        Mass = Moles × Molar mass
                  = 0.0190 moles × 2.01588 g/mol
                  = 0.0383 g
Therefore, mass of hydrogen is 0.0383 g.
As the ratio between 
 and NaH is 1:1. So, we will calculate the moles of NaH as follows. 
              Mass = Moles × Molar mass
                        = 0.0190 moles × 23.99771 g/mol
                        = 0.455 g
Therefore, mass of NaH is 0.455 g.