Grade 10 Chemistry Challenge

What is a chemical reaction?

• A chemical reaction is when substances are heated to produce light.

• A chemical reaction is a method of measuring the weight of substances.

• A chemical reaction is the process of mixing two liquids without any change.

• A chemical reaction is a process where substances (reactants) are transformed into different substances (products) through the rearrangement of atoms.

Identify the products in the reaction: 2H2 + O2 → 2H2O.

• H2

• H2O2

• 2H2O

• O2

What is the law of conservation of mass?

• Mass is conserved in chemical reactions; it cannot be created or destroyed.

• Mass can be destroyed during a reaction.

• Mass is only conserved in physical changes.

• Mass can be created in chemical reactions.

Define an acid according to the Arrhenius theory.

• An acid is a substance that decreases the concentration of H+ ions in solution.

• An acid is a substance that increases the concentration of H+ ions in solution.

• An acid is a substance that increases the concentration of OH- ions in solution.

• An acid is a substance that has a pH greater than 7.

What is the pH scale range for acids?

• 7 to 14

• -1 to 0

• 0 to 6.9

• 6.9 to 10

Explain the difference between strong and weak acids.

• Strong acids fully dissociate in solution; weak acids partially dissociate.

• Weak acids do not react with bases at all.

• Strong acids are always more corrosive than weak acids.

• Strong acids have a higher pH than weak acids.

What is stoichiometry?

• Stoichiometry refers to the measurement of temperature in reactions.

• Stoichiometry is the calculation of reactants and products in chemical reactions.

• Stoichiometry is the study of animal behavior.

• Stoichiometry is the analysis of color changes in chemical reactions.

How do you balance the chemical equation: C3H8 + O2 → CO2 + H2O?

• C3H8 + 4 O2 → 3 CO2 + 2 H2O

• C3H8 + 3 O2 → 2 CO2 + H2O

• C3H8 + 6 O2 → 3 CO2 + 5 H2O

• C3H8 + 5 O2 → 3 CO2 + 4 H2O

What is the molar mass of water (H2O)?

• 22.99 g/mol

• 16.00 g/mol

• 18.02 g/mol

• 20.18 g/mol

Calculate the number of moles in 18 grams of water.

• 0.5 moles

• 3 moles

• 2 moles

• 1 mole