Explanation:
1. Thermochemical equation is balance stoichiometric chemical equation written with the phases of the reactants and products in the brackets along with the enthalpy change of the reaction.
The given correct thermochemical reactions are:


2. Phase change affect the value of the enthalpy change of the thermochemical equation. This is because change in phase is accompanied by change in energy. For example:


In both reaction phase of water is changing with change in energy of enthalpy of reaction.
2 Cr + 3 Cl2 ------> 2CrCl3
Answer: Deposition
Explanation:
Magnesium oxide is an ionic compound with a very high melting point and which requires a large amount of energy for melting.
<h3>What are ionic compounds?</h3>
Ionic compounds are compounds which are formed between oppositely charged ions which are held together by electrostatic forces of attraction between the oppositely charged ions.
Ionic compounds are formed when metal atoms donate electrons to non-metals atoms to form ions.
Magnesium oxide is an ionic compound.
The nature of bonding is ionic bonding.
It has a crystalline lattice structure.
The forces of attraction is electrostatic forces of attraction.
It has a high melting point of 2,852 °C, and thus requires a large amount of energy go melting to occur.
Therefore, magnesium oxide is an ionic compound which requires a large amount of energy for melting.
Learn more about ionic compounds at: brainly.com/question/11638999