Answer:
36.92 mg of oxygen required for bio-degradation.
Explanation:

Mass of benzene = 30 mg = 0.03 g (1000 mg = 1 g )
Moles benzene =
According to reaction 5 moles of benzene reacts with 15 moles of oxygen gas.
Then 0.0003846 mol of benzene will react with:
of oxygen gas
Mass of 0.0011538 moles of oxygen gas:
0.0011538 mol × 32 g/mol = 0.03692 g = 36.92 mg
36.92 mg of oxygen required for bio-degradation.
I think it is D but i'm not sure
hope I helped :)
Bohr model is valid only for hydrogen and hydrogen-like species, but quantum mechanical model can explain all elements....
A mole contains Avogadro’s number of particles of a substance.
Moles = mass / molar mass
molar mass of O2 is 32
therefore moles = 72/32
= 2.25 moles