When 7.00 g of hydrogen react with 70.0 g of nitrogen, hydrogen is considered the limiting reactant because
7.5 mol of hydrogen would be needed to consume the available nitrogen.
7.5 mol of nitrogen would be needed to consume the available hydrogen.
hydrogen would produce 7.5 mol more ammonia than nitrogen.
nitrogen would produce 7.5 mol more ammonia than hydrogen.

7.5 mol of hydrogen would be needed to consume the available nitrogen.

Explanation:

3H₂ + N₂ → 2NH₃

it is clear that 3mol of hydrogen react with 1 mol of Nitrogen to give 2 mol of ammonia.

for H₂:

number of moles = mass / molar mass = (7.00 g) /  (2.00 g/mol) = 3.5 mol.

for N₂:

number of moles = mass / molar mass = (70.00 g) /  (28.00 g/mol) = 2.5 mol.

using cross multiplication

1 mol of  N₂ needs → 3 mol of H₂

2.5 mol of  N₂ needs → ??? mol of H₂

∴ the number of mol of H₂ needed = (3*2.5) / 1 = 7.5 mol

So, the right choice is:

7.5 mol of hydrogen would be needed to consume the available nitrogen.

h let me think