The top number on elements in the periodic table is the atomic number, so when you look at the periodic table you can see that 42 is Mo (Molybdenum), and this is the only element with that atomic number.
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This can be solve using the grahams law, which states that the rate of diffusion of the gas is inversely proportional the square root of the molar mass of the gas. meaning the gas with smaller molar mass is the fastest to diffuse
molar mass of the following
F2 = 38 g/mol
CO2 = 44 g/mol
He = 4 g/mol
SO2 = 64 g/mol
NO = 30 g/mol
NH3 = 17 g/mol
so the fastest is He
Convert to moles first and then use the molar mass of copper to convert to grams
