Test Your Knowledge: Elements, Compounds & Mixtures

1) Which of the following best defines an element?

• A substance composed of only one type of atom.
• Two or more atoms chemically bonded in a fixed ratio.
• A mixture of different substances with no fixed ratio.

2) Which statement is true about mixtures?

• Their components form a completely new substance with unique properties.
• Their components can be separated by physical methods.
• They always exist in a fixed composition ratio.

3) Which of the following describes a compound correctly?

• A single type of atom that cannot be broken down further.
• A substance formed by chemically combining two or more elements in a fixed ratio.
• Two or more substances physically combined in varying proportions.

4) Which process is typically used to break down a compound into simpler substances?

• Filtration
• Distillation
• Electrolysis

5) Which of the following is an example of a mixture?

• Sodium chloride (NaCl)
• Air (combination of gases)
• Water (H₂O)

6) Which statement best describes the properties of an element?

• It can be separated into simpler substances by ordinary chemical methods.
• It has a unique set of properties and cannot be broken down further by chemical means.
• It consists of multiple types of atoms in no specific ratio.

7) Which statement about compounds is incorrect?

• They can be broken down into their constituent elements by chemical means.
• They always contain elements in a fixed ratio.
• They retain all the physical properties of the elements that form them.

8) Which of the following is a compound?

• Helium (He)
• Carbon dioxide (CO₂)
• Brass (an alloy of copper and zinc)

9) What is the smallest unit of an element that still retains its properties?

• Atom
• Molecule
• Ion

10) Which statement is NOT true for a mixture?

• Its composition can vary.
• The components retain their original properties.
• It has a fixed ratio of components.

11) Which method cannot be used to separate a mixture?

• Filtration
• Distillation
• Electrolysis

12) An alloy (such as brass) is an example of a:

• Element
• Compound
• Mixture

13) Which statement correctly compares elements, compounds, and mixtures?

• An element is made of multiple types of atoms; a compound is one type of atom, and a mixture has a fixed ratio.
• A compound can be broken down chemically, while an element cannot; mixtures can be separated physically.
• A mixture has chemical bonds between its components, whereas compounds do not.

14) Which of the following is true for an element?

• It can be broken down into simpler substances by chemical means.
• It contains two or more types of atoms joined chemically.
• It cannot be chemically broken down into simpler substances.

15) Which option is an example of a homogeneous mixture?

• Sand and water
• Saltwater
• Oil and water

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