What is the mass of oxygen in 300 grams of carbonic acid (h2co3)

mass of carbonic acid = 300g

molar mass of H2CO3 = 2H + C + 3 O

= 2 x 1.008+ 12.01 + 3 x  16

= 62.03g/mol

moles of H2CO3 = mass/Molar mass

= 300/62.03

= 4.8364 moles

1 mole H2CO3 has 3 moles Oxygen

4.8364 moles H2CO3 contains  

=   3 x 4.8364  moles Oxygen  =   14.509 moles Oxygen

moles = mass/Molar mass

mass of oxygen = moles x Molar mass of Oxygen

= 14.509 x 16

= 232.15g Oxygen

mass of oxygen in 300g of carbonic acid(H2CO3) = 232.15g

the answer is definitely c.