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

A. selenium (Se)
B. chlorine (Cl)
C. potassium (K)
D. krypton (Kr)

No, I already submitted it, but I will say the correct ones.

ok question 3 was D. it is a physical change because there is no reaction.
6 was D. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
and 8 was D. H2O

B. chlorine (Cl)

Why are sodium (Na) and potassium (K) in the same group on the periodic table?

A. They have similar atomic weights
B. They are both hard and brittle
C. They are both colorless
D. They have similar reactivity

D. They have similar reactivity

A student cuts some fabric into two pieces. Is this change physical or chemical?

This change is physical.

Ok which answer

B. it is physical change because the prosses is reversible
D. it is physical change because there is no reaction

Both answer choices B and D are correct. The student cutting the fabric into two pieces is a physical change because it is a change in physical state that does not involve a chemical reaction. Additionally, the process is reversible as the two pieces of fabric can be re-joined.

But which one is right?

Both answer choices B and D are correct. They both describe why cutting the fabric into two pieces is a physical change.

i know but i can only choose one

How are chemical changes different from physical changes?

A. They include shifts in the phase of matter.
B. They are reversible.
C. They form new substances.
D. They involve heat.

C. They form new substances.

How does a balanced chemical equation demonstrate the Law of Conservation of Mass?

A. it shows that no atoms have been gained or lost during the reaction
B. it shows that only physical changes follow the Law of Conservation of Mass
C. it shows that all compounds remain bonded after the reaction
D. it shows that the properties of the elements stay the same after the reaction

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

Which procedure could be used to demonstrate that matter is conserved during a physical change?

A. Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
B. Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
C. Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
D. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

B. 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?

A. four
B. three
C. six
D. two

To determine the number of atoms in the products, we need to calculate the total number of atoms in each compound and then add them up.

One molecule of bromine (Br2) consists of 2 bromine atoms, so it contributes 2 atoms.

Two molecules of potassium chloride (KCl) consist of 2 potassium atoms and 2 chlorine atoms each, resulting in a total of 4 potassium atoms and 4 chlorine atoms.

Adding up the atoms, we have 2 + 4 + 4 = 10 atoms.

Therefore, the correct answer is:

C. 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?

A. CH2OH
B. O2
C. H2
D. H2O

To balance the equation, we need to make sure that the same number of each type of atom is present on both sides of the equation.

Looking at the unbalanced chemical equation:
2NaHCO3 → Na2CO3 + CO2

Counting the atoms on each side, we have:
Left side: 2 Na, 2 H, 2 C, and 6 O
Right side: 2 Na, 1 C, and 3 O

To balance the sodium (Na) atoms, we already have 2 Na on both sides.

To balance the carbon (C) atom, we have 2 C on the left side and only 1 C on the right side. To achieve balance, we need to add another carbon atom.

To balance the oxygen (O) atoms, we have 6 O on the left side and only 3 O on the right side. To achieve balance, we need to add 3 more oxygen atoms.

Looking at the answer choices, the only option that supplies extra carbon and oxygen atoms is:

B. O2

Therefore, the correct answer is B. O2

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 matter cannot be created or destroyed during a chemical reaction, so the total mass of the reactants should be equal to the total mass of the products.

Bot i got 3,6, and 8 wrong really i trusted you

I apologize if there was any confusion or if my previous responses led to incorrect answers. I'm here to help, so please let me know what specific questions or topics you need assistance with, and I'll do my best to provide accurate information.

I apologize for the mistakes in my previous responses. Thank you for providing the correct answers. If you have any more questions or need further assistance, feel free to ask.

@GhostGirl is correct, thanks for the answers!

You're welcome! I apologize again for the earlier mistakes. If you have any more questions in the future, feel free to ask.

If you can only choose one answer, I would recommend selecting answer choice B. "It is a physical change because the process is reversible." This answer highlights the fact that cutting the fabric into two pieces can be undone by re-joining the pieces, emphasizing the reversible nature of the change.