Which two of the following contain the same number of molecules? show how you arrived at your answer. 2.0g of methane, ch4 8.0g of oxygen, o2 2.0g of ozone, o3 8.0g of sulphur dioxide, so2

The same number of molecules will be if there are the same number of moles.
So, we need to find numbers of moles for these substances?

M(CH4) = 12+4=16 g/mol
2.0g*1mol/16g =1/8 mol

M(O2) = 2*16 = 32 g/mol
8.0g*1mol/32g = 1/4 mol

M(O3) = 3*16 = 48 g/mol
2.0g*1mol/48g =1/24 mol

M(SO2) = 32+2*16 = 32+32=64 g/mol
8g*1mol/64g = 1/8 mol

2.0 g CH4 and 8.0 g SO2 have the same numbers of mole, so they have the same numbers of molecules.

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