Which statement about an atom is correct?(1 point)
Responses
The electron has a negative charge and is found outside of the nucleus.
The electron has a negative charge and is found outside of the nucleus.
The neutron has no charge and is found outside of the nucleus.
The neutron has no charge and is found outside of the nucleus.
The neutron has a negative charge and is found in the nucleus.
The neutron has a negative charge and is found in the nucleus.
The proton has no charge and is found in the nucleus.
11 answers
The correct statement about an atom is:
The electron has a negative charge and is found outside of the nucleus.
The other statements are incorrect because:
The correct statement about the model of a cobalt atom is:
The model should show 27 protons and 32 neutrons.
Here's the reasoning:
The atomic number (27) indicates that cobalt has 27 protons.
The mass number (59) is the total of protons and neutrons. To find the number of neutrons, subtract the number of protons from the mass number:
\[ \text{Neutrons} = \text{Mass number} - \text{Atomic number} = 59 - 27 = 32 \]
So, the model should correctly show 27 protons and 32 neutrons.
The correct statement about lithium sulfide is:
The atoms in lithium sulfide are held together by bonds.
Here’s a brief clarification of the incorrect options:
Both lithium and sulfur form positive ions: Lithium does form a positive ion (Li⁺), but sulfur typically forms a negative ion (S²⁻). So, this statement is inaccurate.
A molecular model of lithium sulfide would have two spheres: A model of lithium sulfide consists of two lithium atoms and one sulfur atom, not just two spheres.
The chemical formula for lithium sulfide is LiS2: The correct formula for lithium sulfide is Li₂S, as it contains two lithium atoms and one sulfur atom.
Thus, the first statement about bonds is the correct one.
The correct response is:
It is a physical change because there is no reaction.
Here's the reasoning:
While the statement about reversibility can apply to physical changes, in this context, the emphasis on "no reaction" makes the second option a more direct and accurate choice. Therefore, the best answer is the one that emphasizes it being a physical change due to the absence of a chemical reaction.
The correct response is:
They form new substances.
Here's the reasoning:
Chemical changes result in the formation of new substances with different chemical properties than the original materials. Examples include rusting of iron, burning of wood, and baking a cake.
Physical changes, on the other hand, do not create new substances. They might involve changes in state (like melting or boiling), shape, or appearance without altering the chemical identity of the substance.
While physical changes can include shifts in the phase of matter, the defining characteristic that distinguishes chemical changes from physical changes is the formation of new substances.
The correct response is:
It shows that no atoms have been gained or lost during the reaction.
Here's the reasoning:
The Law of Conservation of Mass states that mass cannot be created or destroyed in a chemical reaction. A balanced chemical equation demonstrates this law by ensuring that the number of atoms of each element on the reactant side is equal to the number of atoms of that element on the product side. Thus, it shows that all the original atoms are accounted for, and none are lost or gained during the reaction.
