Can someone please point out what I did wrong in a and d. A is going from mole to mole. And d is going from mole to gram.

Answer:
16.96 moles of sodium will needed to react with 4.24 moles of oxygen gas.
Explanation:
[tex]4Na+O_2\rightarrow 2Na_2O[/tex]
Moles of oxygen gas = 4.24 moles
According to reaction , 1 mole of oxygen gas reacts with 4 moles of sodium.
Then 4.24 moles of oxygen gas will react with :
[tex]4.24 mol\times 4= 16.96 mol[/tex] of sodium
16.96 moles of sodium will needed to react with 4.24 moles of oxygen gas.