Test: Matter and Its Composition - Class 7 MCQ

Understanding the states of matter is crucial in everyday life because it influences how materials behave under different conditions, such as temperature and pressure. This knowledge is applied in cooking, construction, and various scientific processes, making it essential for practical applications.

Noble gases, such as helium and neon, exist as single atoms rather than molecules. This characteristic is due to their full outer electron shells, making them chemically inert and unreactive under normal conditions.

As a substance transitions from a solid to a gas, the intermolecular forces weaken significantly. This weakening allows the particles to move freely and spread out, characteristic of the gaseous state, while solids have strong forces that keep particles tightly bound.

A compound is defined as a substance formed when two or more elements chemically combine in a fixed ratio. Compounds have unique properties that differ from those of the individual elements, such as water, which is composed of hydrogen and oxygen in a 2:1 ratio.

In the gaseous state, particles have very weak intermolecular forces, allowing them to move freely in all directions. This characteristic enables gases to expand and fill any available space, distinguishing them from solids and liquids, which have more restricted particle movement.

Gases can be compressed easily because they have very weak intermolecular forces, allowing the particles to be pushed closer together. This property is essential in applications such as gas storage and transportation.

In solids, particles are arranged tightly in fixed positions due to strong intermolecular forces. This arrangement allows solids to maintain their shape and volume, distinguishing them from liquids and gases, where particle arrangement is more dynamic.

In liquids, particles are loosely packed together with weaker intermolecular forces compared to solids, allowing them to slide past one another. This property enables liquids to flow and take the shape of their containers, differentiating them from solids.

Solids have a fixed shape and volume due to the strong intermolecular forces that hold their particles closely packed together. This arrangement allows solids to maintain their shape under normal conditions, as opposed to liquids and gases, which take the shape of their containers.

Liquids generally have a lower density than solids because their particles are less tightly packed. This difference in density is why some objects can float on liquids, depending on their density relative to that of the liquid.

Solids are characterized by their rigidity and incompressibility due to closely packed particles held together by strong intermolecular forces. This structure gives solids a definite shape and volume, unlike liquids and gases.

Intermolecular forces in solids are strong enough to keep the particles tightly packed in fixed positions, preventing them from moving freely. This strong attraction leads to the rigid structure and stability characteristic of solid matter.

Gases are characterized by their very low density due to the large spaces between particles. This low density allows gases to be highly compressible, a property that is essential for various applications, such as in the use of gases as fuels.

An element is defined as a pure substance that cannot be chemically broken down into simpler substances. Elements consist of one type of atom and are the fundamental building blocks of matter, with 118 known elements identified in the periodic table.

Increasing temperature provides more energy to gas particles, causing them to move more rapidly. This increased movement results in higher pressure if the gas is contained, due to more frequent collisions with the container walls.