Question: how many oxygen atoms are present in 88 grams of co2?
Answer: 88 g co2 is 2 moles of co2 ( 1 mole co2 = 44 gm) . Since 1 mole co2 has 2 moles of O atom 2 moles ie 88 gm will have 4 moles which is 4 times avogardos no of atom ie 4* 6.023 *10^23.