Okay
Mr (H2O)= 18g
therefore moles of H2O
is 720.8/18= 40.04mol
the ratio of H2 to O2 to H2O is
2 : 1 : 2
so moles of H2 is same as H2O here
H2= 40.04moles
moles of O2 is half
so 40.04 x 0.5
20.02moles
grams of O2 is
its moles into Mr of O2
that's 20.02 x 32 = 640.64g
B- Carbon nitrogen and oxygen. All organisms are made up of carbon, oxygen is essential to breath, and nitrogen makes up most of earth's atmosphere.
<span>Problem 1) From the given options the one that is proper of a chemist is the option B. testing a sample of water form a well. This activity belongs to the field called analytical chemistry which uses special techniques (instruments and processes) to study (separate, identify and quantify matter).
Problem 2) The only of the given procedures that involves a physical change in one substance is the option D. grinding chalk into a fine powder. In this process the molecules remain being the same (same atoms bonded in the number and way).</span>
The moutain ridge which circles the earth.
