7th grade chemical equation Day 3

Multiple Choice

What are the products formed when zinc reacts with hydrochloric acid?

• Zinc chloride and oxygen gas

• Zinc oxide and hydrogen gas

• Zinc chloride and hydrogen gas

• Zinc sulfate and water

Multiple Choice

What is the chemical equation for the reaction between zinc and hydrochloric acid?

• Zn + HCl → ZnCl + H₂

• Zn + 2HCl → ZnCl₂ + H₂

• Zn + H₂O → ZnO + H₂

• Zn + 2HCl → ZnCl + H₂O

Multiple Choice

How many molecules of hydrochloric acid react with one atom of zinc in the given reaction?

• One

• Two

• Three

• Four

Multiple Choice

What does the law of conservation of matter state?

• Matter can be created and destroyed in ordinary chemical or physical changes.

• Matter cannot be created or destroyed in ordinary chemical or physical changes.

• Matter can only be created in ordinary chemical or physical changes.

• Matter can only be destroyed in ordinary chemical or physical changes.

Multiple Choice

During any ordinary chemical or physical change, what must remain the same before and after the reaction?

• The total mass of the substances involved.

• The total number of atoms.

• The total number of the atoms of each element.

• All of the above.

Multiple Choice

What are the new substances formed during a chemical reaction made up of?

• Different atoms than the atoms of substances that reacted.

• Exactly the same atoms as the atoms of substances that reacted.

• Half the atoms of the substances that reacted.

• Twice the atoms of the substances that reacted.

Multiple Choice

What is the process called when the total number of atoms of each element before and after a reaction is the same?

• Conservation of energy

• Balancing the equation

• Chemical synthesis

• Decomposition reaction

Multiple Choice

When H₂ and Cl₂ react to form 2HCl, what is conserved?

• Energy

• Volume

• Number and types of atoms

• Temperature

Multiple Choice

What does balancing a chemical equation ensure?

• The reaction happens faster

• The total number of atoms of each element is the same before and after the reaction

• The products are always gases

• The reactants are always liquids

Multiple Choice

What is demonstrated by the balanced chemical equation H₂ + Cl₂ → 2HCl?

• The conservation of energy

• The conservation of matter

• The increase in temperature

• The decrease in pressure

Multiple Choice

What forms when a clear, colorless solution of lead nitrate is added to a clear, colorless solution of sodium iodide?

• A) A blue solid, lead iodide

• B) A yellow solid, lead iodide

• C) A green solid, lead iodide

• D) A red solid, lead iodide

Multiple Choice

Which of the following is the balanced chemical equation for the reaction between lead nitrate and sodium iodide?

• A) Pb(NO₃)₂ + NaI → PbI₂ + NaNO₃

• B) Pb(NO₃)₂ + 2NaI → PbI₂ + 2NaNO₃

• C) Pb(NO₃)₂ + NaI → PbI₂ + 2NaNO₃

• D) Pb(NO₃)₂ + 2NaI → PbI₂ + NaNO₃

Multiple Choice

Is the equation Pb(NO₃)₂ + NaI → PbI₂ + NaNO₃ balanced?

• A) Yes

• B) No

• C) Only in acidic conditions

• D) Only in basic conditions