Use the chemical reaction to answer the question.

Question

​CaCO3→CO2​+CaO

A scientist heats 30 grams of calcium carbonate ( CaCO3
) in the chemical reaction shown. What is the total mass of the products?

(1 point)
Responses

10 grams
10 grams

30 grams
30 grams

15 grams
15 grams

60 grams

Answer 1

In a chemical reaction, according to the law of conservation of mass, the total mass of the reactants must equal the total mass of the products.

In this case, the scientist starts with 30 grams of calcium carbonate (CaCO3). During the reaction, this mass will be converted into products, which are carbon dioxide (CO2) and calcium oxide (CaO).

Since no mass is lost or gained in the reaction, the total mass of the products will also be 30 grams.

Therefore, the correct answer is:

30 grams

Answer 2

Use the chemical reaction to answer the question.

4​Fe+3O2→2Fe2O3​

What happens to atoms of Fe and O2 during the reaction?

(1 point)
Responses

They gain mass.
They gain mass.

They are rearranged.
They are rearranged.

They maintain their properties.
They maintain their properties.

They are lost.

Answer 3

In a chemical reaction, atoms are rearranged to form new substances. The law of conservation of mass states that atoms are neither created nor destroyed in a chemical reaction, but they can change their arrangements.

In the given reaction \(4 \text{Fe} + 3 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3\), the iron (Fe) and oxygen (O2) atoms are rearranged to form iron(III) oxide (Fe2O3).

Therefore, the correct answer is:

They are rearranged.

Answer 4

Which is most likely to occur during a chemical reaction?(1 point)
Responses

Mass is conserved.
Mass is conserved.

The original substance maintains its properties.
The original substance maintains its properties.

New atoms are created.
New atoms are created.

Atoms of the original substance are lost.

Answer 5

During a chemical reaction, the law of conservation of mass states that mass is conserved; this means that the total mass of the reactants equals the total mass of the products. Atoms are rearranged to form new substances, but they are not created or destroyed.

Given the options, the most accurate statement is:

Mass is conserved.

Answer 6

Use the chemical reaction to answer the question.

NaHCO3+HC2H3O2→NaC2H3O2+H2O+CO2

A student mixes baking soda ( NaHCO3
) and acetic acid ( HC2H3O2
) to produce a chemical reaction shown. Which statement about the reaction is correct?

(1 point)
Responses

Some atoms gain mass after the reaction.
Some atoms gain mass after the reaction.

Atoms of Na are destroyed during the reaction.
Atoms of Na are destroyed during the reaction.

There are more H atoms after the reaction.
There are more H atoms after the reaction.

The atoms of the reactants are regrouped during the reaction.

Answer 7

In a chemical reaction, atoms are neither created nor destroyed; instead, they are rearranged to form new products. This means the atoms of the reactants are regrouped in the products. The law of conservation of mass applies, so the total number of each type of atom remains the same before and after the reaction.

Given the choices, the correct statement about the reaction is:

The atoms of the reactants are regrouped during the reaction.

Answer 8

Use the chemical reaction to answer the question.

2H2+O2→2H2O

There are four atoms of hydrogen ( H
) before the reaction. How many atoms of hydrogen are present after the reaction?

(1 point)
Responses

5
5

2
2

4
4

8

Answer 9

In the given chemical reaction:

\[ 2 \text{H}_2 + \text{O}_2 \rightarrow 2 \text{H}_2\text{O} \]

There are 2 molecules of hydrogen gas (H2) on the reactant side. Each molecule of H2 contains 2 hydrogen atoms, resulting in:

\[ 2 \text{H}_2 \text{ has } 2 \times 2 = 4 \text{ hydrogen atoms.} \]

On the product side, there are 2 molecules of water (H2O). Each water molecule also contains 2 hydrogen atoms:

\[ 2 \text{H}_2\text{O} \text{ has } 2 \times 2 = 4 \text{ hydrogen atoms.} \]

Since the number of hydrogen atoms is conserved, the number of hydrogen atoms present after the reaction remains 4.

Therefore, the correct answer is:

4