Which of the following equations is a balanced equation?

A. K₂CO₃ + BaCl₂→ 2KCl + 4BaCO₃
Incorrect. This is not a balanced equation.

B. K₂CO₃ + BaCl₂→ 2KCl + BaCO₃
Correct!

C. C K₂CO₃ + 2BaCl₂→ 2KCl + BaCO₃
Incorrect. This is not a balanced equation.

D. K₂CO₃ + 2BaCl₂→ KCl + BaCO₃
Incorrect. This is not a balanced equation.

Which statement is true according to the law of conservation of mass?

A. The number of atoms for each element in the reactants of a chemical reaction must be greater than the number of atoms for each element in the products of that reaction.
Incorrect. According to the law of conservation of mass, the number of atoms for each element in the products must equal the number of atoms for each element in the reactants.

B. The number of atoms for each element in the reactants of a chemical reaction must be less than the number of atoms for each element in the products of that reaction.
Incorrect. According to the law of conservation of mass, the number of atoms for each element in the products must equal the number of atoms for each element in the reactants.

C. The number of atoms for each element in the reactants of a chemical reaction must equal the number of atoms for each element in the products of that reaction.
Correct!

D. The number of atoms for each element in the products of a chemical reaction must be greater than the number of atoms for each element in the reactants of that reaction.
Incorrect. According to the law of conservation of mass, the number of atoms for each element in the products must equal the number of atoms for each element in the reactants.

In the following equation, what coefficient should replace the letter X to balance the equation below?

2H₂O₂ → XH₂O + O₂

A. 3
Incorrect. This would not balance the equation.

B. 4
Incorrect. This would not balance the equation.

C. 1
Incorrect. This would not balance the equation.

D. 2
Correct!

Which of the following is a product in the equation below?

2SO₂ + O₂ + 2H₂O → 2H₂SO₄

A. H₂SO₄
Correct!

B. H₂O
Incorrect. This is a reactant because it is on the left side of the equation.

C. O₂
Incorrect. This is a reactant because it is on the left side of the equation.

D. SO₂
Incorrect. This is a reactant because it is on the left side of the equation.

What are the coefficients needed to balance the following equation?

_________Fe₂O₃ → _________ Fe + _________O₂

A. 2, 3, & 3
Incorrect. If these coefficients were used, there would be 4 iron atoms in the reactants but only 2 in the products.

B. 3, 4, & 2
Incorrect. If these coefficients were used, there would be 6 iron atoms and 9 oxygen atoms in the reactants and 4 iron atoms and 4 oxygen atoms in the products.

C. 1, 2, & 1
Incorrect. If these coefficients were used, there would be 3 oxygen atoms in the reactants but only 2 in the products.

D. 2, 4, & 3
Correct! These coefficients would balance the equation.