Chemical Reactions Quiz

Which of the following is a decomposition reaction?

• 2NaCl→2Na+Cl₂

• H₂+Cl₂→2HCl

• K+Br₂→KBr

• 2H₂O→2H₂+O₂

Identify the reactants in the combustion reaction: CH₄+2O₂→CO₂+2H₂O.

• CH₄ and O₂

• CO₂ and H₂O

• CH₄

• 2O₂

What is the charge of an ion that has gained three electrons?

• -3

• +3

• -1

• +1

If an element in Group 16 has a valency of -2, what does this imply about its electron configuration?

• It has gained 2 electrons

• It has lost 2 electrons

• It has gained 1 electron

• It has lost 1 electron

Balance the following chemical equation: Al+O₂→Al₂O₃

• 4Al+3O₂→2Al₂O₃

• 2Al+O₂→Al₂O₃

• 2Al+3O₂→2Al₂O₃

• 4Al+2O₂→2Al₂O₃

Which of the following best describes a balanced chemical equation?

• The number of atoms of each element is equal on both sides of the equation

• The total mass of reactants is different from the total mass of products

• The number of molecules on each side of the equation is equal

• The total number of electrons is the same on both sides

Using the criss-cross method, what is the correct formula for a compound formed between aluminum (Al) and chlorine (Cl)?

• AlCl

• AlCl₃

• Al₂Cl

• Al₂Cl₃

Write a balanced chemical equation with state symbols for the reaction between hydrochloric acid (HCl) and calcium carbonate (CaCO₃) to form calcium chloride (CaCl₂), carbon dioxide (CO₂), and water (H₂O).

• 2HCl(aq)+CaCO₃(s)→CaCl₂(aq)+CO₂(g)+H₂O(l)

• HCl(aq)+CaCO₃(s)→CaCl₂(aq)+CO₂(g)+H₂O(l)

• 2HCl(l)+CaCO₃(s)→CaCl₂(s)+CO₂(g)+H₂O(g)

• HCl(l)+CaCO₃(s)→CaCl₂(l)+CO₂(g)+H₂O(g)

If an atom has an atomic number of 12 and a mass number of 24, how many neutrons does it have?

• 24

• 12

• 22

• 14

Which type of reaction is represented by the following equation: 2NaBr+Cl₂→2NaCl+Br₂?

• Synthesis

• Decomposition

• Single displacement

• Double displacement