Why are the coefficients before a chemical symbol important?F. They show the number of elements in each molecule. G. They indicate the number of molecules of each substance. H. They describe the number of times each molecule reacts. J. They explain the order in which the reaction takes place

They indicate the number of molecules of each substance

Explanation:

When we write chemical reaction equations, we usually put a number before the symbol of each reactant.

These coefficient shows the number of molecules of that specie that is involved in the balanced reaction equation for the reaction.

These coefficients are important because they are used in carrying out stoichiometric calculations.

particle   p is an electron and particle q is a neutron

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.