ICSE Class 8 Chemistry — Flashcards

A: Matter is anything which has mass, occupies space and can be perceived by our senses. Examples include water, air, wood, sugar, sand, iron, and milk.

A: All living and non-living things of which the universe is composed are matter. Stones, plants, animals, pens, books, water, and air are examples.

A: Greek philosophers believed matter was made of fire, water, air, and earth. Indian philosophers believed in five elements: sky, air, fire, water, and earth.

A: A physical change is a change in which no new substance is formed. Only physical properties such as state, shape, size, or appearance change. The chemical composition remains the same.

A: A chemical change is a permanent change in which a new substance with different properties is formed. The original substance cannot be obtained back by simple physical methods.

A: Ice and water have the same chemical composition, H2O. During melting, only the state changes from solid to liquid. No new substance is formed, so it is a physical change.

A: An element is a pure substance which cannot be converted into anything simpler than itself by any physical or chemical process. It is made up of only one kind of atoms. The smallest unit of an element

A: A compound is a pure substance composed of two or more elements combined chemically in a definite proportion by mass. The smallest unit of a compound is a molecule. Example: water, sodium chloride.

A: A mixture is an impure substance formed by mixing two or more pure substances in any proportion without chemical change. The components retain their individual properties. Mixtures can be homogeneous