How much h2 gas at stp can be produced by the reaction 2 na(s) + 2 h2o(ℓ) −→ h2(g) + 2 naoh(aq) of 4.40 g of na and excess water? answer in units of l?

From the reaction; 
2Na (s) + 2 H2O(l) = H2(g) + 2 NaOH (aq)
The atomic mass of sodium is 22.99 g/mol
The number of moles of sodium will be
  = 4.40/22.99
  = 0.1914 moles 
The mole ratio of sodium and hydrogen is 2: 1 
; therefore, the number of moles of hydrogen = 0.1914/ 2
    = 0.0957 moles
1 mole of hydrogen at s.t.p occupies 22.4 liters, hence 0.0957 moles will occupy; 0.0957 × 22.4 = 2.144 L
Therefore, 2.144  liters of hydrogen gas will be produced