1. Which statement is true?
a. Molc ratios limit the number of significant figures in a calculation.
b. You must know the masses of all the reactants in a chemical equation in order to determine the
masses of all the products.
c. The mole ratio is needed only to solve problems in which the given is a mass in grams and the
unknown is an amount in moles.
d. A molc ratio can only be determined from a correctly balanced chemical cquation.

d. A mole ratio can only be determined from a correctly balanced chemical cquation.

Explanation:

Let's analyze each statement.

a. Mole ratios limit the number of significant figures in a calculation.

This is false because mole ratios are exact quantities that are determined theoretically and are not measured with instruments.

Constants and other exact numbers do not affect the number significant figures in a calculation.

b. You must know the masses of all the reactants in a chemical equation in order to determine the masses of all the products.

This is false. You must know the mass of the limiting reactant Using the mass of the limiting reactant you can determine the masses of all the products in a chemical reaction. And, when both reactants are in the exact theoretical ratio, the mass of any of them can be used to determine the masses of all the products.

c. The mole ratio is needed only to solve problems in which the given is a mass in grams and the unknown is an amount in moles.

This is false. The mole ratio is used to solve problems in which you know either the mass or the moles of some substances taht participate in a chemical reaction and need to determine the mass or moles of others substances for the same reaction.

d. A mole ratio can only be determined from a correctly balanced chemical cquation.

This is TRUE.

The  mole ratio is the numerical relation in which reactants combine with each other or reactants give products in a chemical equation.

That numerical relation is derived from the balanced chemical equation because it is what assures the law of conservation of mass. Two particular reactants will always combine in the same ratio to give certain amount of a product, and that is indicated by the coefficients of the balanced chemical equation.

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.