how many grams of h2 are needed to produce 13.09 g of nh3

MH₂: 2 g/mol
mNH₃: 17 g/mol

3H₂ + N₂ ---> 2NH₃
6g34g

6g H₂ 34g NH₃
Xg 13,09g
X = (6×13,09)/34
X = 2,31g H₂

ELIMINATION is a reaction where a small molecule from from the atoms is removed from a single reactant molecule. 

addition - reaction where two reactants combine to form a single product; usually occurs in unsaturated compounds

condensation - two molecules combine with the release of a small molecule; aka addition-elimination

substitution - one atom or group of atoms in a compound is replaced by a different atom or group ; usually occurs in saturated compounds