MS PS 1-5 Conservation of Mass

The Law of Conservation of Mass states Matter is NEITHER created nor destroyed.

• True

• False

• Matter can be created but not destroyed

• Matter can be destroyed but not created

Answer explanation

The Law of Conservation of Mass asserts that matter cannot be created or destroyed in a chemical reaction. Therefore, the statement is True.

How many magnesium atoms are there in Mg₃N₂?

• 2

• 3

• 4

• 1

Answer explanation

In the compound Mg3N2, the subscript '3' indicates there are 3 magnesium (Mg) atoms. Therefore, the correct answer is 3.

How many nitrogen atoms are in NH₃?

• 0

• 1

• 2

• 3

Answer explanation

NH3, or ammonia, consists of one nitrogen atom and three hydrogen atoms. Therefore, the correct answer is 1.

How many hydrogen atoms are there in the chemical formula C₆H₁₂O₆?

• 10 hydrogen atoms

• 12 hydrogen atoms

• 8 hydrogen atoms

• 14 hydrogen atoms

Answer explanation

In the chemical formula C6H12O6, the subscript '12' next to H indicates there are 12 hydrogen atoms. Therefore, the correct answer is 12 hydrogen atoms.

In a chemical reaction, 4 grams of sodium must combine with how many grams of chlorine to produce 10 grams of table salt?

• 4 grams

• 5 grams

• 6 grams

• 7 grams

Answer explanation

To produce 10 grams of table salt, the total mass of sodium and chlorine must equal 10 grams. With 4 grams of sodium, chlorine must be 10 - 4 = 6 grams. Thus, 6 grams of chlorine is needed.

Final mass of the product in Part B when starting with 52.6 grams of sugar and sulfuric acid.

• Less than 52.6 grams

• Exactly 52.6 grams

• More than 52.6 grams

• 52.6 grams plus the weight of sulfuric acid

4 grams of hydrogen and 32 grams of oxygen will combine to form:

• 36 grams of water

• 32 grams of hydrogen

• 28 grams of oxygen

• 40 grams of hydrogen peroxide

Answer explanation

4 grams of hydrogen and 32 grams of oxygen combine in a 2:16 ratio to form water (H2O). The total mass of the products is 36 grams, confirming that the correct answer is 36 grams of water.

The law of conservation of mass says substances can neither be _______ nor ___________.

• Created; destroyed

• Transformed; altered

• Invented; eliminated

• Manufactured; removed

Answer explanation

The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. Therefore, the correct completion of the statement is 'Created; destroyed', as it reflects this fundamental principle.

Which of the following statements about a balanced chemical equation is correct?

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

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

• Chemical equations can be balanced by changing the subscripts of compounds

• A balanced equation has unequal numbers of atoms on each side

Answer explanation

A balanced chemical equation ensures that the number of atoms of each element is conserved. This means the total number of atoms on the reactant side equals the total on the product side, making the second statement true.

Is this equation balanced?

• Yes

• No

• It depends on the context

• Only if simplified