Why is air pressure greatest at the earth’s surface?
because of the pressure of oxygen
because of the weight of ice crystals
because gravity pulls gas molecules toward the surface
because of pollution

? you expect us to answer this? ? this is your schoolwork, i don't think we can with this, i think it would considering being

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.