Question 1

Question

A)When iron rusts and forms iron oxide, the iron oxide has more mass than the iron. Which statement correctly explains this difference in mass?(1 point)
Responses

The iron atoms in iron oxide have more mass than pure iron.
The iron atoms in iron oxide have more mass than pure iron.

There are more iron atoms in iron oxide than in pure iron.
There are more iron atoms in iron oxide than in pure iron.

Iron oxide has oxygen atoms, and pure iron does not.
Iron oxide has oxygen atoms, and pure iron does not.

The oxygen atoms in iron oxide have more mass than the iron atoms in pure iron.
The oxygen atoms in iron oxide have more mass than the iron atoms in pure iron.
Question 2
A)One molecule of calcium oxide, CaO
, and one molecule of carbon dioxide, CO2
, combine in a chemical reaction to form one substance. Given that matter is neither created nor destroyed, which chemical formula identifies the product of this reaction?(1 point)
Responses

Ca2O3
Ca sub 2 O sub 3

CaCO2
C a C O sub 2

CaCO3
C a C O sub 3

Ca2CO3
Ca sub 2 C O sub 3
Question 3
A)Which statement correctly explains why the ashes of burnt paper have less mass than the original paper?(1 point)
Responses

The ash is created from new atoms that have less mass than the paper.
The ash is created from new atoms that have less mass than the paper.

Some of the atoms in the paper became gases.
Some of the atoms in the paper became gases.

Other atoms combine with the paper to produce the ash.
Other atoms combine with the paper to produce the ash.

Some of the atoms in the paper are destroyed when it burns.
Some of the atoms in the paper are destroyed when it burns.
Question 4
A)
It takes 1 molecule of nitrogen and 3
molecules of hydrogen to produce 2
molecules of ammonia using the following formula:

1N2+ 3H2 → 2NH3

Identify which combination of molecules will produce ammonia with no leftovers?

(1 point)
Responses

8N2
and 4H2
8 n sub 2 and 4 h sub 2

5N2
and 6H2
5 n sub 2 and 6 h sub 2

2N2
and 6H2
2 n sub 2 and 6 h sub 2

4N2
and 4H2
4 n sub 2 and 4 h sub 2
Question 5
A)
In the equation

2H2+1O2→→2H2O

if you change the 2H2
to 3H2
molecules and balance the equation, identify which statement is correct?

(1 point)
Responses

Each oxygen molecule will combine with 2 hydrogen molecules with no leftover molecules.
Each oxygen molecule will combine with 2 hydrogen molecules with no leftover molecules.

The result of the equation will be the same.
The result of the equation will be the same.

It is not possible to produce water without leftover molecules.
It is not possible to produce water without leftover molecules.

The equation will produce three molecules of water.

Answer 1

Here are the answers to your questions:

Question 1
Correct Response: Iron oxide has oxygen atoms, and pure iron does not.
Explanation: When iron rusts, it combines with oxygen from the environment to form iron oxide (rust), which includes both iron and oxygen, leading to an increase in mass.

---

Question 2
Correct Response: CaCO3
Explanation: When CaO (calcium oxide) and CO2 (carbon dioxide) react together, they combine to form CaCO3 (calcium carbonate). This maintains the law of conservation of mass.

---

Question 3
Correct Response: Some of the atoms in the paper became gases.
Explanation: When paper burns, some of its mass is converted to gases (like CO2 and water vapor) which escape into the air, resulting in less mass in the ashes compared to the original paper.

---

Question 4
Correct Response: 8N2 and 4H2
Explanation: According to the reaction, 1 molecule of nitrogen reacts with 3 molecules of hydrogen to produce ammonia. Thus, 8 molecules of nitrogen (N2) would require 24 molecules of hydrogen (4 times the initial 6H2) to produce 16 molecules of ammonia, leading to no leftovers.

---

Question 5
Correct Response: It is not possible to produce water without leftover molecules.
Explanation: If you change the reactants to 3H2, you would not have a whole number of oxygen molecules that could perfectly balance with them without leaving leftover hydrogen, so the statement holds true.

---

If you have any further questions or need clarifications, feel free to ask!