How do I do this a b c

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?