1. Which statement about an atom is correct?(1 point)

Question

Responses

The proton has no charge and is found in the nucleus
The proton has no charge and is found in the nucleus

The neutron has a negative charge and is found in the nucleus.
The neutron has a negative charge and is found in the nucleus.

The neutron has no charge and is found outside of the nucleus.
The neutron has no charge and is found outside of the nucleus.

The electron has a negative charge and is found outside of the nucleus.
The electron has a negative charge and is found outside of the nucleus.
Question 2
2. Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?(1 point)
Responses

The model should show 59 protons and 27 neutrons.
The model should show 59 protons and 27 neutrons.

The model should show 27 protons and 27 neutrons.
The model should show 27 protons and 27 neutrons.

The model should show 32 protons and 59 neutrons.
The model should show 32 protons and 59 neutrons.

The model should show 27 protons and 32 neutrons.
The model should show 27 protons and 32 neutrons.
Question 3
3. In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct? (1 point)
Responses

Both lithium and sulfur form positive ions.
Both lithium and sulfur form positive ions.

The atoms in lithium sulfide are held together by bonds.
The atoms in lithium sulfide are held together by bonds.

The chemical formula of lithium sulfide is LiS2
The chemical formula of lithium sulfide is LiS 2

A molecular model of lithium sulfide would have two spheres.
A molecular model of lithium sulfide would have two spheres.
Question 4
4. Use the periodic table to answer the question: 


Which element has the same number of valence electrons as bromine (Br)?

(1 point)
Responses

chlorine (Cl)
chlorine (Cl)

krypton (Kr)
krypton (Kr)

selenium (Se)
selenium (Se)

potassium (K)
potassium (K)
Question 5
5. Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
Responses

They have similar atomic weights.
They have similar atomic weights.

They are both hard and brittle.
They are both hard and brittle.

They have similar reactivity.
They have similar reactivity.

They are both colorless.
They are both colorless.
Question 6
6. A student cuts some fabric into two pieces. Is this change physical or chemical and why?(1 point)
Responses

It is a physical change because there is no reaction.
It is a physical change because there is no reaction.

It is a chemical change because the size changes.
It is a chemical change because the size changes.

It is a physical change because the process is reversible.
It is a physical change because the process is reversible.

It is a chemical change because there is no phase change.
It is a chemical change because there is no phase change.
Question 7
7. How are chemical changes different from physical changes?(1 point)
Responses

They are reversible.
They are reversible.

They form new substances.
They form new substances.

They include shifts in the phase of matter.
They include shifts in the phase of matter.

They involve heat.
They involve heat.
Question 8
8. How does a balanced chemical equation demonstrate the Law of Conservation of Mass?(1 point)
Responses

it shows that no atoms have been gained or lost during the reaction
it shows that no atoms have been gained or lost during the reaction

it shows that only physical changes follow the Law of Conservation of Mass
it shows that only physical changes follow the Law of Conservation of Mass

it shows that the properties of elements stay the same after the reaction
it shows that the properties of elements stay the same after the reaction

it shows that all compounds remain bonded after the reaction
it shows that all compounds remain bonded after the reaction
Question 9
9. Sodium reacts with chlorine to form the compound sodium chloride, or salt. The chemical formula below shows how the two elements combine into a compound.

2Na + Cl2 → 2NaCl

If the total mass of the reactants is 58.44 amu, what will be the total mass of the products?

(1 point)
Responses

60 amu
60 amu

29.22 amu
29.22 amu

116.88 amu
116.88 amu

58.44 amu
58.44 amu
Question 10
10. Which lab procedure could be used to demonstrate that matter is conserved during a physical change? (1 point)
Responses

Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.

Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.

Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Question 11
11. One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)
Responses

two
two

six
six

four
four

three
three
Question 12
12. Use the unbalanced chemical equation to answer the question.

2NaHCO3 → Na2CO3 + CO2

Which of the following can be added to the products to balance the equation?
(1 point)
Responses

O2
O 2

CH2OH
CH 2 OH

H2
H 2

H2O
H 2 O
Question 13


13. The image is a model of sulfuric acid that has a chemical formula of H2SO4. Why is creating models, like the one shown in the image above important in understanding substances? Select all that apply!

(3 points)
Responses

Models help to represent molecules, which are not visible, and can help design new components.
Models help to represent molecules, which are not visible, and can help design new components.

Models tell us the exact number of protons present.
Models tell us the exact number of protons present.

Models help to demonstrate how atoms react with each other
Models help to demonstrate how atoms react with each other

Models tell the type of bonds that are formed by different elements.
Models tell the type of bonds that are formed by different elements.
Question 14
14. Which of the following statements are true according to the law of conservation of mass in chemical reactions? Select all that apply!(3 points)
Responses

The total mass of the reactants is equal to the total mass of the products in a chemical reaction.
The total mass of the reactants is equal to the total mass of the products in a chemical reaction.

During a chemical reaction, mass is created or destroyed.
During a chemical reaction, mass is created or destroyed.

The number of atoms of each element remains the same before and after the reaction.
The number of atoms of each element remains the same before and after the reaction.

Chemical reactions can change the type of atoms involved, but not their total mass.
Chemical reactions can change the type of atoms involved, but not their total mass.

If a chemical reaction occurs in an open container, some mass may be lost to the surroundings.

Answer 1

Here are the correct answers for each question based on the information provided:

Question 1:

• Correct Answer: The electron has a negative charge and is found outside of the nucleus.

Question 2:

• Correct Answer: The model should show 27 protons and 32 neutrons. (Mass number = protons + neutrons; 59 - 27 = 32 neutrons)

Question 3:

• Correct Answer: The atoms in lithium sulfide are held together by bonds.

Question 4:

• Correct Answer: chlorine (Cl) (Bromine and chlorine are both in Group 17 and have 7 valence electrons.)

Question 5:

• Correct Answer: They have similar reactivity. (Both sodium and potassium are alkali metals and react similarly.)

Question 6:

• Correct Answer: It is a physical change because there is no reaction.

Question 7:

• Correct Answer: They form new substances.

Question 8:

• Correct Answer: it shows that no atoms have been gained or lost during the reaction.

Question 9:

• Correct Answer: 58.44 amu (According to the Law of Conservation of Mass, mass is conserved in a chemical reaction.)

Question 10:

• Correct Answer: Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water. (This is a demonstration of no mass lost in a physical change.)

Question 11:

• Correct Answer: six (Br2 has 2 Br atoms; KCl has 2 K + 2 Cl atoms, totaling 2 + 2 + 2 = 6 atoms.)

Question 12:

• Correct Answer: H2O (Adding H2O can help balance the equation.)

Question 13:

• Correct Answers:
  • Models help to represent molecules, which are not visible, and can help design new components.
  • Models help to demonstrate how atoms react with each other.
  • Models tell the type of bonds that are formed by different elements.

Question 14:

• Correct Answers:
  • The total mass of the reactants is equal to the total mass of the products in a chemical reaction.
  • The number of atoms of each element remains the same before and after the reaction.
  • Chemical reactions can change the type of atoms involved, but not their total mass.

These answers reflect an understanding of basic chemistry concepts related to atomic structure, chemical reactions, and the law of conservation of mass.