Conservation of Mass

Which of the following is true regarding the law of conservation of mass?

• It dictates that the number of molecules on each side of a chemical equation must be the same.

• It dictates that the number of atoms of each element must be the same on both sides of a chemical equation.

• It states that the mass of the reactants must remain constant in order for a chemical reaction to proceed.

• It does not apply to chemical reactions.

Tags

NGSS.MS-PS1-5

Which of the following may indicate that a chemical reaction has occurred?

• release of energy as light

• a color change

• gas bubble formation

• All of the above

Tags

NGSS.MS-PS1-2

Which of the following is a product in the reaction described by the word equation below?

iron + copper(II) sulfate → iron(II) sulfate + copper

• iron(II) sulfate

• copper

• iron

• Both iron(II) sulfate and copper

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What does CH₄ represent in the balanced chemical equation shown below?

C + 2H₂ → CH₄

• one atom of CH₄

• five atoms of CH₄

• one molecule of CH₄

• 1 g of CH₄

Tags

NGSS.MS-PS1-1

Which of the following is not true regarding a properly written chemical equation?

• It must be balanced.

• It must contain proper chemical formulas.

• It must show the formation of a precipitate or a gas.

• It should represent known data.

In a chemical equation, the formula of a substance in water solution is followed by the symbol

• (l).

• (s).

• (g).

• (aq).

The Greek letter delta (Δ) above the arrow in a chemical equation means

• “yields” or “produces.”

• a catalyst is used in the reaction.

• the reaction releases energy as heat.

• the reactants are heated.

What will be the result of the reaction described by the following chemical equation?

PCl₅(g) ⇌ PCl₃(g) + Cl₂(g)

• a mixture of PCl₅(g) and PCl₃(g) only

• a mixture of PCl₃(g) and Cl₂(g) only

• a mixture of PCl₅(g), PCl₃(g), and Cl₂(g)

• PCl₅(g) only

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

What is the total number of molecules represented by the following equation?

2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(g)

• 4

• 15

• 18

• 33

Which set of coefficients will balance the equation below?

NaOH + Cu(NO₃)₂ → Cu(OH)₂ + NaNO₃

• 1, 1, 1, 1

• 1, 2, 2, 1

• 2, 1, 2, 1

• 2, 1, 1, 2

Tags

NGSS.HS-PS1-7