The correct answers to the 11 questions are:
1. The model should show 27 protons and 32 neutrons.
2. The atoms in lithium sulfide are held together by bonds.
3. chlorine (Cl)
4. They have similar reactivity.
5. It is a physical change because there is no reaction.
6. They form new substances.
7. It shows that no atoms have been gained or lost during the reaction.
8. 116.88 amu.
9. Find the mass of the water that remains.
10. four.
11. H2O.
Matter Interactions Unit Test
Science 8 Q1 / Matter Interactions
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 27 protons and 27 neutrons.
The model should show 27 protons and 32 neutrons.
The model should show 59 protons and 27 neutrons.
The model should show 32 protons and 59 neutrons.
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.
A molecular model of lithium sulfide would have two spheres.
The chemical formula for lithium sulfide is LiS 2 .
The atoms in lithium sulfide are held together by bonds.
Which element has the same number of valence electrons as bromine (Br)?
(1 point)
Responses
selenium (Se)
chlorine (Cl)
krypton (Kr)
potassium (K)
Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
Responses
They have similar atomic weights.
They are both hard and brittle.
They are both colorless.
They have similar reactivity.
A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
Responses
It is a chemical change because the size changes.
It is a chemical change because there is no phase change.
It is a physical change because the process is reversible.
It is a physical change because there is no reaction.
How are chemical changes different from physical changes?(1 point)
Responses
They are reversible.
They involve heat.
They include shifts in the phase of matter.
They form new substances.
How does a balanced chemical equation demonstrate the Law of Conservation of Mass?(1 point)
Responses
it shows that all compounds remain bonded after the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that only physical changes follow the Law of Conservation of Mass
it shows that no atoms have been gained or lost during the reaction
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
58.44 amu
60 amu
29.22 amu
116.88 amu
Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
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
four
three
six
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
H 2
CH 2 OH
O 2
H2O
what are the correct answers to all 11 questions
6 answers
Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
what is the correct answer?
Responses
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
what is the correct answer?
The correct answer is: Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Matter Interactions Unit Test
Science 8 Q1 / Matter Interactions
Use the chemical equation to complete the activity.
2Cu+S→Cu2S
Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction, all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2S). In 1–2 sentences, explain the law that the scientist used to predict that the product of the reaction would be 15.9 grams of copper sulfide.
Science 8 Q1 / Matter Interactions
Use the chemical equation to complete the activity.
2Cu+S→Cu2S
Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction, all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2S). In 1–2 sentences, explain the law that the scientist used to predict that the product of the reaction would be 15.9 grams of copper sulfide.
The scientist used the Law of Conservation of Mass to predict that the product of the reaction would be 15.9 grams of copper sulfide. This law states that in a chemical reaction, matter is neither created nor destroyed, so the total mass of the reactants must equal the total mass of the products.
8. 58.44 amu
31 answers