Sodium (Na) and potassium (K) are in the same group on the periodic table because they have similar reactivity. Elements in the same group often share similar chemical properties, which is primarily due to having the same number of valence electrons. In the case of Na and K, both are alkali metals that have one electron in their outermost shell, leading to similar reactions, particularly with water and halogens.
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 colorless. They are both colorless. They are both hard and brittle. They are both hard and brittle. They have similar reactivity.
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A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point) Responses 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. It is a physical change because the process is reversible.
The correct response is: It is a physical change because the process is reversible.
Cutting fabric changes its size and shape but does not alter its chemical composition. Therefore, it is considered a physical change.
How are chemical changes different from physical changes?(1 point) Responses They involve heat. They involve heat. They are reversible. They are reversible. They include shifts in the phase of matter. They include shifts in the phase of matter. They form new substances.
The correct response is: They form new substances.
Chemical changes result in the formation of new substances with different properties, while physical changes do not change the chemical composition of the substances involved.
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 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 all compounds remain bonded after the reaction
The correct response is: it shows that no atoms have been gained or lost during the reaction.
A balanced chemical equation demonstrates the Law of Conservation of Mass by ensuring that the number of atoms of each element is the same on both sides of the equation, indicating that matter is neither created nor destroyed in a chemical 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 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 will be 58.44 amu.
According to the Law of Conservation of Mass, the total mass of the reactants must equal the total mass of the products in a chemical reaction. Thus, if the total mass of the reactants is 58.44 amu, the total mass of the products will also be 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 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 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.
The correct procedure to demonstrate that matter is conserved during a physical change is: Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
This procedure shows that the mass remains the same before and after the physical change (melting) occurs, thus demonstrating the conservation of matter.
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