In the following chemical reaction, how many moles of n2 are needed to completely react with 3 moles of h2? n2 + 3 h2 2 nh3
a. 1
b. 2
c. 3
d. 6

a) 1

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

According to stoichiometry :

3 moles of hydrogen reacts with 1 mole of nitrogen to give 2 moles of ammonia.

Thus 1 mole of hydrogen are needed to completely react with 3 moles of nitrogen.

4d^55s^1 ( third choice)