Answer:

Explanation:
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In this case, since the combustion reaction of methanol is:

In such a way, since there is 1:3/2 mole ratio between methanol and oxygen, we can compute the moles of oxygen that are needed to burn 2.56 moles of methanol as shown below:

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It's a chemical change because it's changing the object's property.
C:H:O = 40/12 : 6,7/1 : 53,3/16 = 3,33 : 6,7 : 3,33 ≈ 1 : 2 : 1
CH₂O
The magnesium dissolves to form magnesium chloride and hydrogen gas is released.
Mg + 2HCl -----> MgCl2 + H2(g).