How any moles of H2O will be produced from 12.3 moles of HCL reacting with Ca(OH)2?

\large \boxed{\text{12.3 mol HCl}}  

Explanation:

We need a balanced chemical equation with moles.

            2HCl +Ca(OH)₂ ⟶ CaCl₂ + 2H₂O

n/mol:    12.3

The molar ratio is 2 mol H₂O:2 mol HCl.

there is none because earth is stationary and flat.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.