You got the answer correct. If you would double check
given:C (12 g/mol) H (1 g/mol).
12(8) + 1(8) = 104 g/mol
and for C2H4
12(2)+1(4) = 28g/mol
Also, chemical formula of styrene is<span> C6H5CH=CH2.</span>
To find the number of neutrons, subtract the number of protons from the mass number. number of neutrons=40−19=21.
the answer is actually 118 look it up