States of Matter

# States of Matter Video Lecture - Crash Course: Class 9

153 videos

## FAQs on States of Matter Video Lecture - Crash Course: Class 9

 1. What are the three states of matter?
Ans. The three states of matter are solid, liquid, and gas. In solids, particles are closely packed and have a fixed shape and volume. Liquids have particles that are close together but can move around, giving them a fixed volume but not a fixed shape. Gases have particles that are far apart and can move freely, allowing them to take the shape and volume of their container.
 2. How is the state of matter determined?
Ans. The state of matter is determined by the arrangement, motion, and energy of the particles that make up a substance. The particles in a solid are tightly packed and vibrate in fixed positions. In a liquid, the particles are close together but can move past each other. In a gas, the particles are far apart and move freely. The temperature and pressure also play a role in determining the state of matter.
 3. What is the difference between evaporation and boiling?
Ans. Evaporation and boiling are both processes in which a liquid changes into a gas, but they differ in the amount of heat energy required. Evaporation occurs at the surface of a liquid when the particles with higher kinetic energy escape into the air. It takes place at any temperature, even below the boiling point. Boiling, on the other hand, occurs throughout the liquid when the vapor pressure equals the atmospheric pressure. It requires a specific temperature, known as the boiling point, and the addition of heat energy.
 4. How does melting occur?
Ans. Melting is the process in which a solid changes into a liquid. It occurs when heat energy is added to a solid, causing the particles to gain enough energy to overcome the attractive forces holding them in a fixed position. As a result, the particles start moving more freely, and the solid gradually turns into a liquid. The temperature at which melting occurs is known as the melting point.
 5. What is the difference between a physical change and a chemical change?
Ans. A physical change is a change in the physical properties of a substance, such as its shape, size, or state of matter, without altering its chemical composition. Melting, freezing, boiling, and condensation are examples of physical changes. On the other hand, a chemical change involves a transformation of one or more substances into new substances with different chemical properties. Examples of chemical changes include rusting of iron, burning of wood, and digestion of food.

## Crash Course: Class 9

153 videos

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