Chapter 8 Test

A chemical equation is balanced when the

• coefficients of the reactants equal the coefficients of the products.
• same number of each kind of atom appears in the reactants and in the products.
• products and reactants are the same chemicals.
• subscripts of the reactants equal the subscripts of the products.

In the chemical equation 2Mg(s) + O₂ (g) → 2MgO(s),

• Mg represents the product magnesium.
• the reaction yields magnesium.
• Mg represents the reactant magnesium.
• O2 represents the product oxygen gas.

You mix solution A with solution B in a beaker. Which of the following observations does not help you prove that a chemical reaction has occurred?

• The beaker becomes warm.
• You see gas bubble out of solution.
• Solution A and solution B when mixed turn yellow.
• None of the above; all help prove that a chemical reaction has occurred.

To balance a chemical equation, you must

• adjust the coefficients.
• adjust the number of products.
• adjust the number of reactants.
• adjust the subscripts.

In which type of reaction do two or more compounds react to form one product?

• synthesis
• decomposition
• combustion
• single-displacement

The formation of an gas product in a chemical reaction is represented by the symbol

• (aq).
• (s).
• (g).
• (l).

Which of the following indicates that a chemical equation is balanced?

• The numbers of atoms of each element are the same on both sides of the equation.
• All of the coefficients are the same.
• The numbers of molecules on each side of the equation are equal.
• The sums of the coefficients on each side of the equation are equal.

From a complete and correctly written chemical equation, you can obtain the

• chemical formulas of the reactants and products.
• relative amounts of the reactants and products.
• physical states of the reactants and products.
• All of the answers

In the expression 3CO₂ , the numbers 3 and 2 are, respectively,

• a subscript and a coefficient.
• a coefficient and a subscript.
• two subscripts.
• two coefficients.

Which of the following equations represents the balanced equation for the reaction of iron and oxygen?

• 2Fe + O₂ → Fe₂O₃
• Fe + 3O₂ → Fe₂O₃
• 4Fe + 3O₂ →2Fe₂O₃
• 3Fe + 3O₂ → 2Fe₂O₃