Answer:

Explanation:
You calculate the energy required to break all the bonds in the reactants.
Then you subtract the energy needed to break all the bonds in the products.
CH₃CH₂OH + 3O₂ ⟶ 2CO₂ + 3H₂O
Bonds: 5C-H 1C-C 1C-O 1O-H 3O=O 4C=O 6O-H
D/kJ·mol⁻¹: 413 347 358 467 495 799 467

It is true, because a strong magnet that can be turned off and on is an electromagnet.
Answer: it would stop producers from producing food.
Explanation: why? Without the action of the producers to turn sunlight into food, the producers would die, and consumers that rely on them would lose their food source and die too.
Na2CO3 Na= 23*2=46 C=12 O=16*3=48. Na2CO3=106. 46/106*0.175=0=403