Which of the following is considered acidic?(1 point)
Responses
Lime Water
Lime Water
Ammonia
Ammonia
Soap
Soap
Vinegar
Vinegar
Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
Responses
They are both hard and brittle.
They are both hard and brittle.
They have similar atomic weights.
They have similar atomic weights.
They have similar reactivity.
They have similar reactivity.
They are both colorless.
They are both colorless.
They have similar reactivity.
Which element has the same number of valence electrons as bromine (Br)?
(1 point)
Responses
potassium (K)
potassium (K)
chlorine (Cl)
chlorine (Cl)
selenium (Se)
selenium (Se)
krypton (Kr)
chlorine (Cl)
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
The chemical formula for lithium sulfide is LiS2.
The chemical formula for lithium sulfide is LiS 2 .
Both lithium and sulfur form positive ions.
Both lithium and sulfur form positive ions.
A molecular model of lithium sulfide would have two spheres.
A molecular model of lithium sulfide would have two spheres.
The atoms in lithium sulfide are held together by bonds.
The atoms in lithium sulfide are held together by bonds.
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 59 protons and 27 neutrons.
The model should show 59 protons and 27 neutrons.
The model should show 27 protons and 32 neutrons.
The model should show 27 protons and 32 neutrons.
The model should show 27 protons and 27 neutrons.
The model should show 27 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 32 neutrons.
The chemical formula for carbonic acid is H2CO3
. How many compounds are represented by this formula?(1 point)
Responses
6
6
1
1
3
3
2
2
2
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 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.
It is a chemical change because there is no phase change.
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 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 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
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
29.22 amu
29.22 amu
58.44 amu
58.44 amu
116.88 amu
116.88 amu
60 amu
58.44 amu
Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses
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 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 an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
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 piece of ice. Let the ice melt. Find the mass of the liquid water.
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
six
six
four
four
two
two
three
Four
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
H2O
H 2 O
H2
H 2
CH2OH
CH 2 OH
O2
O2
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)