Answer:


Explanation:
<u>First mixture</u>:
40 wt% methanol - 60 wt% water 200 kg


<u>Second mixture</u>:
70 wt% methanol - 30 wt% water 150 kg


Final mixture:




If, the compositions are constant, the only variables are the mass of each mixture used in the final one, so there can be only one independent balance.
The answer is 3. The releasing of energy means exothermic reaction. So the ΔH should be negative. And the greatest quantity of energy released means that the greatest number. So according to the table I, the answer is 3.