Chemical Reactions Quiz

Which of the following most likely represents a chemical change?

• Water boiling

• Sugars Digested by saliva

• Mud Drying to dirt

• Ice cream melting

How many atoms of Iron are on the products side of the following equation? Fe₂O₃ + 3H₂ → 2Fe + 3H₂O

• 2

• 3

• 4

• 1

How many oxygen atoms are on the reactants side of the following equation: Fe₂O₃ + 3H₂ → 2Fe + 3H₂O

• 4

• 6

• 3

• 1

How many atoms of hydrogen are on the reactants side of the following equation: Fe₂O₃ + 3H₂ → 2Fe + 3H₂O

• 6

• 3

• 2

• 4

Two molecules of sodium azide (NaN₃) break down into sodium (Na) and nitrogen gas (N₂) during a reaction. How many sodium (Na) atoms are produced in the reaction?

• 1 Na atom

• 2 Na atoms

• 3 Na atoms

What symbol in a chemical equation separates the reactants from the products?

• =

• -->

• ≥

• +

What is the number +4+ in SiCl₄?

• a subscript

• a coefficient

• a product

• a reactant

Cecil writes the equation for the reaction of hydrogen and oxygen below.

H₂ + O₂ → H₂O

Why does the teacher ask him to balance the equation by including the correct coefficients?

• to show that most molecules exist in pairs.

• to show that most compounds exist in pairs.

• to show that atoms are conserved in chemical reactions.

• to show that atoms are created in chemical reactions.

Leslie incorrectly balances an equation as 2C₄H₁₀ + 12O₂ → 8CO₂ + 10H₂O.

Which coefficient should she change?

• 2

• 8

• 10

• 12

In a process called photosynthesis, plants use carbon dioxide and water, along with energy from sunlight, to produce sugar and oxygen. Photosynthesis is represented by the equation

What must a plant need to produce 4 molecules of sugar?

• 6 molecules of CO₂

• 6 molecules of H₂O

• 18 molecules of CO₂

• 24 molecules of H₂O