Answer:
2
Step-by-step explanation:
A chemical equation comprises of substances called reactants and other substances called products. The reactants combine together to form the products. However, according to the law of conservation of matter, the number of atoms of each element in the reactant side must be equal to that on the product side. This is called a BALANCED EQUATION.
However, to balance an equation, COEFFICIENTS are used to ensure the number of atoms of each element equate on both sides. In this question where the following unbalanced equation was given:
BaCl2(aq) + Na2CO3(aq) → BaCO3(s) + NaCl(aq)
It can be observed that the number of atoms of sodium (Na) does not equate on both sides. Hence, we use a coefficient of 2 on NaCl to equate them. The balanced equation reads:
BaCl2(aq) + Na2CO3(aq) → BaCO3(s) + 2NaCl(aq)