Volume of tank =
(given)
Since,
So,

For
:

The significant rule for multiplication, states that the number of significant figures in the answer obtained by multiplication is determined by the value with the lowest number of significant digits.
Since, the minimum number of decimal places in the above multiplication operation is 1 so, the final result must be upto 1 decimal place only.

Hence, volume in
is 243.5.
Answer:
2Mg + O2 → 2MgO
Explanation:
In all conbustion you should know, that reactans are an specific compound and O2, so the products must be CO2 and H2O, or in this case, the corresponding oxide.