What is the percent by mass of C in oc- tane (C8H18)? The molecular weight of
carbon is 12.0107 g/mol and of hydrogen
1.00794 g/mol.

Is 9 correct? and can someone me with 10? it’s due tomorrow, you

Element before carbon on the periodic table

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?