Chemical Reactions Quiz

What is always true in a chemical reaction?

• New atoms are created

• Mass is destroyed

• Atoms are rearranged

• The product is always a gas

Which type of reaction occurs when one compound breaks down into simpler substances?

• Double replacement

• Combustion

• Decomposition

• Synthesis

Which of the following is a sign of a chemical reaction?

• Melting ice

• Mixing water and salt

• Color change

• Evaporation

In which system can gas escape, possibly making the mass appear to change?

• Closed system

• Open system

• Balanced system

• Isolated system

What is the molar mass of H₂O?

• 16 g/mol

• 17 g/mol

• 18 g/mol

• 20 g/mol

In a chemical reaction, the limiting reactant is:

• The reactant that is present in excess

• The product that forms last

• The reactant that runs out first and limits the amount of product

• The reactant that is not used at all

If the theoretical yield is 25 g and the actual yield is 20 g, what is the percent yield?

• 80%

• 125%

• 50%

• 100%

What unit is used as the basic measurement for quantifying matter in chemical reactions?

• Grams

• Moles

• Liters

• Atoms

In the equation 4Fe + 3O₂ → 2Fe₂O₃, what is the mole ratio of Fe to O₂?

• 3:4

• 2:3

• 4:3

• 1:2

How many moles of O₂ are required to produce 16 moles of SO₃ in: 2SO₂ + O₂ → 2SO₃?

• 8 mol

• 16 mol

• 32 mol

• 4 mol