Which discovery would have the greatest impact on reducing the negative consequences of plastic?(1 point)
Responses
the discovery of more ways to incorporate plastic in everyday goods
the discovery of more ways to incorporate plastic in everyday goods
the discovery of more ways to reuse plastic
the discovery of more ways to reuse plastic
the discovery of new sources for the raw materials of plastic
the discovery of new sources for the raw materials of plastic
the discovery of a new bacteria that consumes plastic waste
the discovery of a new bacteria that consumes plastic waste
you sure
I apologize for the mistake. The correct answer is:
the discovery of new ways to reuse plastic.
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 32 neutrons.
The model should show 27 protons and 32 neutrons.
The model should show 59 protons and 27 neutrons.
The model should show 59 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 27 neutrons.
The model should show 27 protons and 32 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
A molecular model of lithium sulfide would have two spheres.
A molecular model of lithium sulfide would have two spheres.
The chemical formula for lithium sulfide is LiS2.
The chemical formula for lithium sulfide is LiS 2 .
The atoms in lithium sulfide are held together by bonds.
The atoms in lithium sulfide are held together by bonds.
Both lithium and sulfur form positive ions.
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
krypton (Kr)
krypton (Kr)
potassium (K)
potassium (K)
chlorine (Cl)
chlorine (Cl)
selenium (Se)
The element that has the same number of valence electrons as bromine (Br) is chlorine (Cl).
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 are both colorless.
They are both colorless.
They have similar reactivit
They have similar reactivity.
A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
Responses
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.
It is a chemical change because the size changes.
It is a chemical change because the size changes.
It is a physical change because there is no reaction.
It is a physical change because there is no reaction.
How are chemical changes different from physical changes?(1 point)
Responses
They form new substances.
They form new substances.
They are reversible.
They are reversible.
They include shifts in the phase of matter.
They include shifts in the phase of matter.
They involve heat
They form new substances.
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 the elements stay the same after the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that all compounds remain bonded after the reaction
It shows that no atoms have been gained or lost during the reaction, demonstrating the Law of Conservation of Mass.
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
116.88 amu
116.88 amu
58.44 amu
58.44 amu
60 amu
60 amu
29.22 amu
The total mass of the products can be calculated by summing the atomic masses of the products in the chemical equation. In this case, we have 2 NaCl molecules, each with a molecular mass of 58.44 amu. Therefore, the total mass of the products will be 2 * 58.44 amu = 116.88 amu. Hence, the correct answer is 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 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 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 an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
The procedure that could be used to demonstrate that matter is conserved during a physical change is:
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
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
four
four
three
three
six
six
two
In the reaction, one molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine. The products formed are two molecules of potassium bromide (KBr) and one molecule of chlorine gas (Cl2).
The molecular formula for potassium bromide is KBr, which contains one atom of potassium (K) and one atom of bromine (Br). Therefore, the two molecules of potassium bromide would have a total of two potassium atoms and two bromine atoms.
The molecular formula for chlorine gas is Cl2, which consists of two chlorine (Cl) atoms bonded together.
Combining all the atoms, we have:
2 potassium atoms + 2 bromine atoms + 2 chlorine atoms = 6 atoms.
Therefore, there are six atoms in the products.
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
H2
H 2
H2O
H 2 O
O2
O 2
CH2OH
To balance the equation, we need to ensure that the number of each type of atom is the same on both sides.
In the given unbalanced equation:
2NaHCO3 -> Na2CO3 + CO2
We have:
- 2 sodium atoms (Na) on the left
- 2 hydrogen atoms (H) on the left (2 multiplied by the coefficient 2 in NaHCO3)
- 2 carbon atoms (C) on the right (2 in Na2CO3)
- 8 oxygen atoms (O) on the left (2 multiplied by the coefficient 2 in NaHCO3) and 3 on the right (1 in Na2CO3 + 2 in CO2)
By examining the options, we can see that adding H2O (water) to the products will help balance the equation. It will account for the missing oxygen atoms on the right side. Adding 5 H2O molecules will give us 5 additional oxygen atoms on the right side:
2NaHCO3 -> Na2CO3 + CO2 + 5H2O
Now, the balanced equation becomes:
2NaHCO3 -> Na2CO3 + CO2 + 5H2O
Question
The image shows a model of sulfuric acid. In the middle is one yellow ball. Four red balls are attached to the yellow ball with sticks. Two of the red balls have a blue ball attached with sticks. In total, there is 1 yellow, 4 red, and 2 blue balls.
The image is a model of sulfuric acid that has a chemical formula of H2SO4. In 1-2 sentences, explain why creating models, like the one shown in the image above, is important in understanding substances.
(2 points)
Creating models like the one shown in the image is important in understanding substances because it helps visualize the arrangement and connectivity of atoms in a molecule, providing a tangible representation that aids in comprehending the chemical structure and properties of the substance.
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.
(2 points)