Page 108 - Innovator's Science-8

Grasp-Up

Ma er: Anything that has mass and occupies space.
Mixture: A combina on of two or more substances mixed physically without chemical change.
Component: Each substance or part present in a mixture.
Heterogeneous mixture: A mixture in which different components can be seen and are not uniformly
distributed.
Homogeneous mixture: A mixture in which the components are evenly distributed and cannot be
dis nguished separately.
Alloy: A uniform mixture of two or more metals, or of a metal and a non-metal.
Pure substance: A kind of ma er that has the same type of par cles and cannot be separated into other
substances by physical means.
Element: A pure substance made up of only one kind of atom.
Compound: A pure substance formed when two or more elements combine chemically in a fixed ratio.
Mineral: A naturally occurring substance obtained from the earth, usually solid and inorganic, from which
metals and other materials are extracted.
Electrolysis: The process of using electricity to split a compound into its elements.

Points to Reflect

• The world around us is made of matter, which has mass and occupies space.
• Most substances are mixtures made of two or more components physically combined.
• Mixtures are of two types — heterogeneous (non-uniform) and homogeneous (uniform).
• Alloys are uniform mixtures of metals used in making strong and durable materials.
• Pure substances contain only one kind of particle and have definite properties.
• Elements are pure substances made of one type of atom; examples include iron, gold, and oxygen.
• Compounds are pure substances formed when elements combine chemically in a fixed proportion.
• Water is a compound of hydrogen and oxygen in a 2:1 ratio.
• Physical changes, such as melting or freezing, do not produce new substances.
• Electrolysis of water produces hydrogen and oxygen gases, proving that water is a compound.
• Minerals are natural substances obtained from the earth; metals and many useful materials are derived
from them.
• Understanding elements, compounds, and mixtures helps scientists and engineers create new materials
and technologies.

NCERT Textbook Questions (Solved)

Let Us Enhance Our Learning

1. Consider the following reac on where two substances, A and B, combine to form a product C:
A + B → C
Assume that A and B cannot be broken down into simpler substances by chemical reac ons. Based on
this informa on, which of the following statements is correct?
i. A, B, and C are all compounds, and only C has a fixed composi on.

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