Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is anything that has mass, occupies space, and can be perceived by our senses. It is composed of tiny particles called atoms or molecules.
The space between the molecules of matter is called Intermolecular Space. It is minimum in solids and maximum in gases.
The force of attraction between the molecules of matter is called Intermolecular Force of Attraction. This force is strongest in solids and weakest in gases.
Solids have a definite shape and a definite volume because their particles are closely packed with negligible intermolecular space.
Liquids have a definite volume but no definite shape; they take the shape of the container. This is because the intermolecular forces are weaker than in solids.
Gases have neither a definite shape nor a definite volume. They are highly compressible because of very large intermolecular spaces.
Diffusion is the process of intermixing of particles of two different types of matter on their own. The rate of diffusion is fastest in gases.
The change of state from solid to liquid is called Melting, and liquid to gas is called Vaporization or Evaporation.
Sublimation is the process where a solid directly changes into a gas without passing through the liquid state, such as in the case of or .
📐Formulae
💡Examples
Problem 1:
Explain why a gas can be compressed easily, but a solid cannot.
Solution:
Gases have very large intermolecular spaces compared to solids. When pressure is applied, these spaces can be reduced significantly. In solids, the particles are already closely packed with negligible space, making them incompressible.
Explanation:
Compressibility depends on the amount of empty space between particles. In , the distance is large, whereas in , the distance is nearly zero.
Problem 2:
Why does the smell of hot sizzling food reach you several meters away, but to get the smell from cold food you have to go close?
Solution:
The rate of diffusion increases with temperature. Particles of hot food have higher kinetic energy () and move faster than particles of cold food.
Explanation:
Since , an increase in temperature increases the velocity () of the particles, allowing them to travel further and faster through the air.
Problem 3:
Calculate the density of a solid block if its mass is and its volume is .
Solution:
Explanation:
Density is defined as mass per unit volume. By dividing the total mass by the total volume, we find the density of the substance.