1L of air contains 21% of oxygen by volume at STP. What is the number of moles of oxygen in 1L of air?

Air contains 21% of oxygen by volume. The number of moles of O_(2) present in 5L of air at STP conditions

Calculate the number of moles of oxygen in 11200 cc volume at STP.

The volume of two moles of oxygen at STP

What is the percentage of oxygen in the exhaled air ?

What is the percentage of Nitrogen and Oxygen in the air?

A person takes 15 breaths per minute. The volume of air inhaled in each breath is 448 ml and contains 21% of oxygen by volume. The exhaled air contains 16% of oxygen by volume. If all the oxygen is used in the combustion of sucrose, how much of the Sucrose is burnt in the body per day & how much heat is evolved. Delta H_(com) of sucrose is = 6000 kJ mol^(-1) . Take temperature to be 300 K throughout. [Assuming V_("inhaled air") = V_("exhalded air"), P_(atm) = 1atm ]