Quick answer: Exothermic reactions mean that heat has escaped the system. The answer is A. Heat is released.
Answer:

Explanation:
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In this case, according to the given STP (standard pressure and temperature), it is possible for us to realize that the equation to use here is the Avogadro's law as a directly proportional relationship between moles and volume:

In such a way, given the initial volume and both initial and final moles, we can easily compute the final volume as shown below:

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Answer:
Postassium bisulphate - KHSO4 - can be used as an food preservative to protect the food from micro-organisms.
Answer:
No reaction is observed
Explanation:
The benzene ring is aromatic. Being an aromatic ring, the benzene ring is remarkably stable to all reactions that destroy the aromatic ring.
Alkenes are oxidized to alkanols in the presence of KMnO4 but this reaction does not occur with benzene. However, substituted benzenes having hydrogen atoms attached to the substituent carbon atom can be oxidized to the corresponding carboxylic acid.