How many moles of nitrogen, n, are in 74.0 g of nitrous oxide, n2o?

2 N₂ (g) + O₂ (g) ⇌ 2 N₂O

When nitrogen and oxygen reacts nitrous oxide is formed.

Molar mass of N = 14.0067 g/mol and N₂ = 28.0134
molar mass of O = 15.9998 g/mol 
molar mass of N₂O =28.0134 + 15.9998 =  44.0132 g/mol 

Now we first find the percent composition of N in N2O. 

(14.0067(2)/44.0128)100 = 63.65% of N 
 use the percent to find the mass of N in 74.0g of N₂O 

63.65% = 0.6365

74.0g (.6365) = 47.10g of N 

Now convert the g to mol 
47.10g (1 mol/14.0067g) = 3.36 mol N

the correct answer is a

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.