In the treatment of patients oxygen masks give oxygen to the patient. this oxygen does what

What is one function of the embedded proteins

During which phase does earth see more than half of the moon's surface? 1)first quarter2)third quarter3)waxing gibbous4)waning crescent

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?