Lithium and Nitrogen React in a Combination Reaction to Produce

Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6Li(s) + (g) → N(s)
How many moles of lithium are needed to produce 0.40 mol of N when the reaction is carried out in the presence of excess nitrogen?

A) 0.13
B) 1.2
C) 0.20
D) 0.067
E) 2.4