Question

what is the percent by mass of carbon in c10 h14 n2?

Answer 1

C10H14N2
the relative formula masses:
C10 = (12x10) = 120
H14 =  (14x1)  = 14
N2   =  (14x2)  =  28

%composition of carbon =  100 x (14 + 28 / 120) = 0.35
%composition of carbon = 35%
hope that helps

Answer 2

took the test and its 74.02% actually...