Answer :
first step: calculate the number of moles of sodium reacted
moles=mass/molar mass
31.5g/23g/mol =1.37moles
from the reaction above the reacting ratio of Na to H2 is 2:1 therefore moles of H2 is 1.37/2=0.685
At STP 1 mole = 22.4L what about 0.685 moles
22.4 x0.685=15.344L
moles=mass/molar mass
31.5g/23g/mol =1.37moles
from the reaction above the reacting ratio of Na to H2 is 2:1 therefore moles of H2 is 1.37/2=0.685
At STP 1 mole = 22.4L what about 0.685 moles
22.4 x0.685=15.344L