8th Science

What is a compound?

• A single element in its pure form

• A mixture of different substances

• A substance formed when two or more different elements chemically bond together

• A solution of acids and bases

An element is defined as:

• A substance that can be broken down into simpler substances

• A mixture of different elements

• A pure substance that cannot be broken down by chemical means

• A solution with a pH of 7

Which of the following describes a heterogeneous mixture?

• A mixture with uniform composition

• A mixture where components are not uniformly distributed

• A single phase substance

• A pure element

A homogeneous mixture is characterized by:

• Distinct, separate phases

• Uniform distribution of components

• Varying compositions

• Fixed proportions of elements

Matter is:

• Anything that can be seen

• Anything that has mass and occupies space

• Only solid substances

• A specific type of element

Adhesion refers to:

• The attraction between similar molecules

• The tendency of different substances to cling together

• The surface tension of liquids

• The pressure exerted by a gas

Cohesion is:

• The force that holds liquids in a container

• The attraction between molecules of the same substance

• The separation of mixtures

• The process of dissolving

Surface tension is:

• The pressure exerted by a gas

• The cohesive force at the surface of a liquid

An acid is a substance that:

• Donates protons (H⁺ ions) in solution

• Accepts protons (H⁺ ions)

• Has a pH greater than 7

• Is neutral in nature

A base is defined as:

• A substance that donates protons

• A substance that has a pH of 7

• A substance that accepts protons or donates hydroxide ions (OH⁻)

• A mixture of acids and bases