What is the percent composition of carbon in heptane, c7h16?

a. 12%
b. 68%
c. 19%
d. 84%.

Explanation:

1) Determine the molar mass of the heptane

element   # of atoms    atomic mass        total mass      

  C              7                  12.011 g/mol         7×12.011 g/mol = 84.077 g/mol

  H             16                  1.008 g/mol         16×1.008 g/mol = 16.128 g/mol

                                                                   Molar mass =    100.205 g/mol

2) Percent of carbon, %

           = (84.077 g/mol / 100.205 g/mol )×100 = 83.83 %

the answer is 1260

you spend 7 hours in school for 1 school day with 5 school days in 1 school week with 36 school weeks in a school year.

7*5*36= 1260 it's all about multiplying