______ is the heaviest gas.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Radon gas
At the same temperature and pressure, a gas is heavier (denser) when its molecules are heavier, so the gases can be compared by their molar masses:
Radon (Rn) — about 222 g/mol; a radioactive noble gas, about 7.5 times as heavy as air and the heaviest of the naturally occurring gases
Sulphur dioxide (\(\ce{SO2}\)) — 64 g/mol
Nitrogen oxides — nitric oxide (\(\ce{NO}\)) 30 g/mol, nitrogen dioxide (\(\ce{NO2}\)) 46 g/mol
Carbon monoxide (\(\ce{CO}\)) — 28 g/mol, a little lighter than air