The gas carbon dioxide is a pure substance. Which of the following is true about carbon dioxide ?

Carbon and oxygen are chemically bonded in it.

Carbon and oxygen retain their original identity in it

It can be separated into carbon and oxygen using physical methods

The proportion of carbon and oxygen is different in different samples of the gas

Read the chemical equation. 2c2h2 + 5o2 → 4co2 + 2h2o which of the following statements would be correct if one mole of c2h2 was used in this reaction? one mole of oxygen was used in this reaction. five moles of oxygen were used in this reaction. four moles of carbon dioxide were produced from this reaction. two moles of carbon dioxide were produced from this reaction.