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

60 grams
60 grams

30 grams
30 grams

10 grams
10 grams

15 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 is starting with 30 grams of calcium carbonate (CaCO3). As it decomposes, it produces carbon dioxide (CO2) and calcium oxide (CaO), but the total mass of the products will still equal the mass of the reactants.

Therefore, the total mass of the products will be 30 grams.

The correct response 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 maintain their properties.
They maintain their properties.

They are rearranged.
They are rearranged.

They gain mass.
They gain mass.

They are lost.

Answer 3

During a chemical reaction, atoms are rearranged to form new substances, but they do not lose or gain mass overall. Instead, the same atoms are simply combined in different ways to create products from the reactants.

In the given reaction:

$$4,\text{Fe}+3,{\text{O}}_2\to 2,{\text{Fe}}_2{\text{O}}_3$$

the iron (Fe) and oxygen (O2) atoms are rearranged to form iron(III) oxide (Fe2O3).

Thus, the correct response is:

They are rearranged.

Answer 4

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

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

Mass is conserved.
Mass is conserved.

New atoms are created.
New atoms are created.

Atoms of the original substance are lost.

Answer 5

During a chemical reaction, the most likely occurrence is that the mass of the substances involved is conserved. According to the law of conservation of mass, the total mass of the reactants must equal the total mass of the products, and atoms are rearranged but not created or destroyed.

Therefore, the correct response 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

The atoms of the reactants are regrouped during the reaction.
The atoms of the reactants are regrouped during the reaction.

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

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

Atoms of Na are destroyed during the reaction.

Answer 7

In the provided chemical reaction:

$${\text{NaHCO}}_3+{\text{HC}}_2{\text{H}}_3{\text{O}}_2\to {\text{NaC}}_2{\text{H}}_3{\text{O}}_2+{\text{H}}_2\text{O}+{\text{CO}}_2$$

The correct statement is that the atoms of the reactants are regrouped during the reaction. This means that the atoms from sodium bicarbonate (NaHCO3) and acetic acid (HC2H3O2) are rearranged to form new products, which include sodium acetate (NaC2H3O2), water (H2O), and carbon dioxide (CO2).

The other options are incorrect because:

• The total number of hydrogen atoms (H) remains the same before and after the reaction since mass and atoms are conserved.
• No atoms gain mass since mass is conserved during the reaction.
• Atoms of sodium (Na) and all other atoms are not destroyed; they are simply rearranged.

Therefore, the correct response 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

8
8

4
4

5
5

2

Answer 9

In the given chemical reaction:

$$2H_2+O_2\to 2H_{2}O$$

Before the reaction, there are 4 atoms of hydrogen, as there are 2 molecules of $H_2$ (each containing 2 hydrogen atoms).

After the reaction, the products formed are 2 molecules of water $(2H_{2}O)$, and each water molecule contains 2 hydrogen atoms. Therefore, in the products:

• There are $2\text{ molecules}\times 2\text{ H atoms/molecule}=4\text{ H atoms}$.

Thus, the number of hydrogen atoms remains the same before and after the reaction.

Therefore, the correct answer is:

4