Answer: The correct option is A.
Explanation: Moles of Iron nail can be calculated by using the formula:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ...(1)
Given mass of iron nail = 100 g
Molar mass of iron = 56 g/mol
[tex]\text{Number of moles}=\frac{100g}{56g/mol}[/tex]
Number of moles of iron nail = 1.79 moles
The chemical equation for the formation of rust if given by:
[tex]4Fe(s)+3O_2(g)\rightarrow 2Fe_2O_3(s)[/tex]
By Stoichiometry of the reaction,
4 moles of iron reacts with 3 moles of oxygen gas to produce 2 moles of rust.
So, 1.79 moles of iron will react with = [tex]\frac{3}{4}\times 1.79[/tex] = 1.3425 moles of oxygen gas.
For oxygen gas,
Molar mass = 32 g/mol
Mass of oxygen can be calculated by using equation 1, we get
[tex]1.3425mol=\frac{\text{Given mass}}{32g/mol}[/tex]
Mass of oxygen gas = 43 grams
Hence, the correct option is a.
