Chemistry worksheet focusing on elements, compounds, and mixtures with multiple-choice questions.

It looks like you've uploaded a worksheet titled "QUESTION: Elements" with multiple-choice questions about basic chemistry concepts, particularly focusing on elements, compounds, and mixtures. Since I can't view images directly, I'll assume the content is as described in your text.

Let me solve and explain each question based on typical content from such worksheets:

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Question 1:

A substance composed entirely of one type of atom is called:
A. compound
B. element
C. mixture
D. solution

✔ Correct Answer: B. element

Explanation:
An element is a pure substance made up of only one type of atom. For example, oxygen (O₂) consists only of oxygen atoms. A compound contains two or more different types of atoms chemically bonded (e.g., H₂O), while a mixture involves substances physically combined without chemical bonding.

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Question 2:

The number of protons found in an atom is called its:
A. atomic mass
B. atomic number
C. charge
D. shell

✔ Correct Answer: B. atomic number

Explanation:
The atomic number defines the number of protons in the nucleus of an atom. It determines the identity of the element. For example, hydrogen has an atomic number of 1, meaning it has one proton.

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Question 3:

Which of the following is NOT a state or phase of an element?
A. solid
B. liquid
C. gas
D. plasma

✔ Correct Answer: D. plasma

Wait — this depends on context.
Plasma *is* a state of matter (like gas, but ionized), so technically, plasma is a phase of matter. However, if the question assumes only the three common states (solid, liquid, gas), then plasma might be considered "not" one of them in basic science curricula.

But scientifically, plasma IS a state of matter, so if the options include plasma, and the question asks which is NOT a state, then none are incorrect.

However, assuming the intent is to test basic knowledge:
✔ Answer: D. plasma — *if the curriculum doesn’t cover plasma.*

But note: Plasma is actually a fourth state of matter (e.g., in stars, lightning). So this may be a trick question.

👉 Best answer: D. plasma — if the expectation is that students know only solid, liquid, gas.

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Question 4:

Different states of the same element are called:
A. isotopes
B. allotropes
C. ions
D. nuclei

✔ Correct Answer: B. allotropes

Explanation:
Allotropes are different structural forms of the same element in the same physical state. For example, diamond and graphite are allotropes of carbon. Isotopes refer to atoms with the same number of protons but different neutrons. Ions are charged atoms. Nuclei are the centers of atoms.

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Question 5:

Groups of elements that have similar properties are called:
A. families
B. periods
C. groups
D. periods

✔ Correct Answer: A. families OR C. groups

Note: Both "families" and "groups" are correct terms used interchangeably in the periodic table. For example, Group 1 is the alkali metals family.

But since both A and C are listed, and they mean the same thing in this context, likely the intended answer is:

✔ Answer: A. families or C. groups — depending on what’s taught.

In most textbooks:
- Groups = vertical columns
- Families = names for groups (e.g., halogens, noble gases)

So both are acceptable, but "families" is often used when referring to shared properties.

👉 If only one answer is allowed, A. families is the best choice.

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✔ Final Answers:

1. B. element
2. B. atomic number
3. D. plasma *(assuming plasma isn't expected)*
4. B. allotropes
5. A. families *(or C. groups – both are valid)*

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💡 Summary:
This worksheet tests foundational chemistry vocabulary. Understanding terms like element, atomic number, allotropes, and families is key to mastering the periodic table and matter classification.

Let me know if you'd like this formatted into a printable answer key!