What mass of oxygen contain same number of molecule as 42g of nitrogen?

Answer 1

Both nitrogen and oxygen exist at standard temperature and pressure as diatomic molecules. Therefore, the relative masses of equal numbers of molecules of the substance will the same as the ratios of their atomic masses, which are 15.9994 for oxygen and 14.0067 for nitrogen. The mass of oxygen that contains the same number of molecules as 42 g of nitrogen is 42(15.9994/14.0067) or 48 g, to the justified number of significant digits.

Answer 2

The molar mass of oxygen is 32 g/mol and the molar mass of nitrogen is 28 g/mol. If 42g of nitrogen contains the same number of molecules as a certain mass of oxygen, then you would need to determine the ratio of their molar masses and use that to calculate the mass of oxygen required. In this case, you would need 48g of oxygen to contain the same number of molecules as 42g of nitrogen.