Option D: 46.0 g
The balanced chemical reaction is as follows:
[tex]2Na+2H_{2}O\rightarrow 2NaOH+H_{2}[/tex]
The standard temperature and pressure conditions are 273.15 K and 1 atm respectively.
First calculate the number of moles of [tex]H_{2}[/tex] formed at STP,
Since, [tex]PV=nRT[/tex]
Here, P is pressure, V is volume, n is number of moles, R is gas constant and T is temperature.
Rearranging the equation,
[tex]n=\frac{PV}{RT}=\frac{(1 atm)(22.4 L)}{(0.082 atm L K^{-1} mol^{-1})(273.15 K)}=1 mol[/tex]
Thus, number of moles of [tex]H_{2}[/tex] gas will be 1 mol.
From the chemical reaction, 2 mol of Na gives 1 mol of [tex]H_{2}[/tex] thus, number of moles of Na will be 2 mol.
Molar mass of Na is 22.99 g/mol thus, mass can be calculated as follows:
[tex]m=n\times M=2 mol\times 22.99 g/mol=45.98 g\approx 46 g[/tex]
Therefore, mass of Na is 46.0 g.
