Class 9 Science : Practice Questions and Answers

A covalent bond is formed by sharing electrons between atoms.

Calcium chloride contains one calcium atom and two chlorine atoms.

Neon is a noble gas and is chemically inert.

Oxygen, nitrogen, and chlorine all exist as diatomic molecules.

The empirical formula represents the simplest whole-number ratio of atoms in a compound.

Oxygen molecules consist of two oxygen atoms bonded together.

The nucleus contains protons and neutrons.

An atom is the smallest particle of an element that retains its chemical properties.

Chromatography separates substances based on different rates of movement.

A homogeneous mixture has a uniform composition throughout.

Water is a compound made of hydrogen and oxygen chemically combined.

Concrete is a heterogeneous mixture because its components are not uniformly distributed.

Air is a homogeneous mixture of gases uniformly distributed.

Hydrogen is a pure substance consisting of only one type of atom.

A colloid is a heterogeneous mixture with very small suspended particles.

In a heterogeneous mixture, components are unevenly distributed.

Copper is a pure element made of only copper atoms.

Higher temperature increases particle energy, causing evaporation.

Melted wax solidifies again on cooling, making the change reversible.

Water boils at 100°C under standard atmospheric pressure.