Asked by GhostGirl

Which element has the same number of valence electrons as bromine (Br) ?
A. selenium (Se)
B. chlorine (Cl)
C. potassium (K)
D. krypton (Kr)
Answered by GhostGirl
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
Answered by GhostGirl
A student cuts some fabric into two pieces. Is this change physical or chemical?
Answered by GhostGirl
Ok which answer
B. it is physical change because the prosses is reversible
D. it is physical change because there is no reaction
Answered by GhostGirl
But which one is right?
Answered by GhostGirl
i know but i can only choose one
Answered by GhostGirl
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.
Answered by GhostGirl
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
Answered by GhostGirl
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.
Answered by GhostGirl
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
Answered by GhostGirl
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
Answered by GhostGirl
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.
Answered by GhostGirl
Bot i got 3,6, and 8 wrong really i trusted you
Answered by GhostGirl
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
Answered by Sucker4Nialler
@GhostGirl is correct, thanks for the answers!
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