What is the mass of carbon dioxide which contains the same number of molecules as are contained in 40 g of oxygen?

Sure, let's solve this step by step:

1. First, we need to find the number of moles in 40g of Oxygen. We know that the molar mass of Oxygen (O2) is 32g/mol. So, the number of moles of Oxygen = mass/molar mass = 40g / 32g/mol = 1.25 mol.

2. According to Avogadro's law, equal volumes of all gases, at the same temperature and pressure, have the same number of molecules. Therefore, the number of molecules in 1.25 mol of any gas is the same.

3. Now, we need to find the mass of Carbon Dioxide (CO2) that contains the same number of molecules. The molar mass of CO2 is 44g/mol.

4. Therefore, the mass of CO2 = number of moles * molar mass = 1.25 mol * 44g/mol = 55g.

So, the mass of carbon dioxide which contains the same number of molecules as are contained in 40 g of oxygen is 55g.