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.
Answer:
1st order
Explanation:
because magnesium has a coefficient of 1, it is first order
hydrochloric acid has a coefficient of 2, so it is second order
overall the reaction is third order (1+2)
They will attract each other when brought close but when they touch the glass rod will become a negative charge and will repel each other