I THINK 18 OR 21 I AM SORRY IF I AM WRONG BRO
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.
Answer:
10
Explanation:
In image
Take atomic mass or molar mass
of Al =27
It's the number of Protons of that atom..