13) A 3.82-g sample of magnesium nitride is reacted with 7.73 g of water:

Mg3N2 + 3H2O 2NH3 + 3MgO

The yield of MgO is 3.60 g. What is the percent yield in the reaction?

A) 94.5

B) 78.4

C) 46.6

D) 49.4

E) 99.9

14) What is the empirical formula of a compound that is 66.6% C, 11.2% H, and 22.2% O by mass?

A) C4HO

B) C6HO2

C) C8H16O2

D) C6H11O

E) C4H8O

15) A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is ________.

A) C2H4O2

B) CH2O

C) C2H3O4

D) C2H2O4

E) CHO2