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Matter Interactions Unit Test
6 of 166 of 16 Items
Question
Use the periodic table to answer the question.
An illustration shows the periodic table.
Which element has the same number of valence electrons as bromine (Br)?
(1 point)
Responses
krypton (Kr)
krypton (Kr)
chlorine (Cl)
chlorine (Cl)
potassium (K)
potassium (K)
selenium (Se)
The element that has the same number of valence electrons as bromine (Br) is chlorine (Cl). Bromine is in group 17, also known as the halogens, and has 7 valence electrons. Chlorine, which is also in group 17, has the same number of valence electrons. So, the correct response is:
chlorine (Cl)
Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
Responses
They have similar reactivity.
They have similar reactivity.
They are both colorless.
They are both colorless.
They have similar atomic weights.
They have similar atomic weights.
They are both hard and brittle.
The reason why sodium (Na) and potassium (K) are in the same group on the periodic table is that they have similar reactivity. Elements in the same group of the periodic table share similar chemical properties, such as reactivity, due to having the same number of valence electrons. So, the correct response is:
They have similar reactivity.
Question
A student cuts some fabric into two pieces. Is this change physical or chemical?(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 chemical change because there is no phase change.
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 the process is reversible.
The student cutting the fabric into two pieces is a physical change. This is because there is no chemical reaction occurring during this process. It is simply a change in physical state without altering the chemical composition of the fabric. Therefore, the correct response is:
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.
The primary difference between chemical changes and physical changes is that chemical changes result in the formation of new substances with different chemical compositions, while physical changes do not involve the formation of new substances. Therefore, the correct response is:
They form new substances.
Question
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 all compounds remain bonded after the reaction
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 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 only physical changes follow the Law of Conservation of Mass