The correct answer for the question that is being presented above is this one: "The number of sodium ions is equal to the number of formula units of salt." The statement that best describes the relationship between the substances in the equation is that the number of sodium ions is equal to the number of formula units of salt.
Answer : The number of sodium ions is equal to the number of formula units of salt.
Explanation : In the given reaction of NaCl the statement which describes it the best is that the number of sodium ions is found to be same along with the formula units in the product side.
+ ----> NaCl.
Its clear from the equation that one mole of Na and one mole of Cl combines together to give the product, which is one mole of NaCl. The number of ions on both the sides are equal.