问题详情

Which of the following best explains why equal masses of O2 and CO2 at the same temperature and in the same-size vessel had different pressures？ The pressure exerted by the O2 was:
A.less, because there were fewer O2 molecules per gram than there were CO2 molecules per gram.
B.less, because there were more O2 molecules per gram than there were CO2 molecules per gram.
C.greater, because there were fewer O2 molecules per gram than there were CO2 molecules per gram.
D.greater, because there were more O2 molecules per gram than there were CO2 molecules per gram.请帮忙给出正确答案和分析，谢谢！