Answer: The correct statement is 7.5 mol of hydrogen would be needed to consume the available nitrogen.
Step-by-step explanation:
To calculate the number of moles, we use the equation:

Given mass = 7 grams
Molar mass = 2 g/mol
Putting values in above equation:

Given mass = 70 grams
Molar mass = 28 g/mol
Putting values in above equation:

- For the given chemical reaction:

By Stoichiometry of the reaction:
1 mole of nitrogen is consumed by 3 moles of hydrogen
2.5 moles of nitrogen is consumed by =
of nitrogen gas.
Hydrogen is considered as a limiting reagent because it limits the formation of products and will be totally consumed by a less quantity of excess reagent.
Hence, the correct statement is 7.5 mol of hydrogen would be needed to consume the available nitrogen.