7. The balanced equation N_2 (g)+3H_2 (g)⟶2NH_3 (g) means which of the following?

One gram of nitrogen reacts with three grams of hydrogen to form two grams of ammonia
One mole of nitrogen reacts with three moles of hydrogen to form two moles of ammonia
The equation means both a and b
The equation means neither a nor b

The correct answer is: The equation means both a and b.