Which of the following is a characteristic of elements? A) Composed of multiple kinds of atoms B) Can exist in solid, liquid, or gaseous states C) Has variable melting points D) Always homogeneous and impure

B) Can exist in solid, liquid, or gaseous states

Fill in the blank: An element is a pure substance composed of only one kind of ______.

Atom

True or False: A compound can be separated into its constituent elements by physical methods.

False. A compound can only be separated by chemical or electrochemical methods.

Riddle: I am a mixture of two or more substances where the composition can vary and I lack a fixed formula. What am I?

A mixture

What distinguishes a true solution from a colloid?

A true solution is homogeneous.

• True solutions are clear liquids.

• Colloids scatter light visibly.

• Centrifugation separates colloids.

Which type of separation method would you use to separate iron filings from a mixture of iron and sulphur?

Magnetic separation

Fill in the blank: The process used to separate a liquid mixture into its components based on boiling points is called ______.

Distillation

True or False: Colloids can settle under gravity and are visible to the naked eye.

False. Colloids do not settle under gravity and may not be visible to the naked eye.

Riddle: I am a pure substance made from two or more elements chemically bonded. What am I?

A compound

What is the primary difference between mixtures and compounds in terms of composition?

Mixtures have variable composition, while compounds have a fixed composition.

Which of the following is a noble gas? A) Nitrogen B) Argon C) Oxygen D) Hydrogen

B) Argon

Fill in the blank: The method of separating colored components in a mixture, such as ink, is called ______.

Chromatography

True or False: All mixtures are homogeneous.

False. Mixtures can be homogeneous or heterogeneous.

Riddle: I change from solid to vapor without becoming liquid, often used to separate substances. What am I?

Sublimation

What type of mixture contains particles larger than 10⁻⁷ m and appears heterogeneous?

Suspension

Fill in the blank: The smallest particle that participates in a chemical reaction is called an ______.

Atom

Which separation technique would you use to clarify a cloudy liquid by allowing solids to settle?

Sedimentation and Decantation

True or False: Solutions always contain visible particles that can settle out over time.

False. Solutions are homogeneous and do not have visible particles that settle.

Riddle: I am the dispersed substance in a solution, while the liquid is my medium. What am I?

Solute

What is the main characteristic of metalloids?

Metalloids have properties intermediate between metals and non-metals.