AP Board Class 9 Physical Science Chapter 1 Matter Around Us

While studying science students will frequently come across the question “what is matter?” The topic is usually introduced in primary classes, but the concept gradually becomes more advanced and there are many new related topics that are discussed. As such, the topic of ‘matter’ is discussed in greater detail in Andhra Pradesh Board Class 9 Physical Science textbook Chapter 1, which is titled as Matter Around Us helps students to learn about the definition of matter, states of matter and other topics like;

• The composition of matter.
• Changes in the state of matter.
• Properties of Solid, Liquid and Gas.
• Forces of attraction between particles

What Is Matter?

As per the popular definition, matter is said to be any substance that takes up space and has mass. There are mainly three states of matter, which are liquid, solid and gas. Matter is also made up tiny particles called atoms. Usually, these particles have space between them, but there is also a force of attraction that exists between them. This force of attraction between the particles is more in solids, less in liquids and almost negligible in gases. Particles move continuously and freely in liquids and gases.

Notably, the states of matter are not permanent. A solid can be changed to liquid and liquid to gas when the temperature or pressure is changed.

Properties of Matter

When we talk about the properties of matter, we have to look at it, considering the properties of the three states of matter.

• Solids: They have definite shape and volume.
• Liquids: The have definite volume, but no definite shape.
• Gases: They have neither definite shape nor volume.

Classification Of Matter

Matter is classified as either pure substances, which have single substance or mixture, which contains more than one substances. A mixture is either homogeneous or heterogenous, whereas pure substances can be classified into elements and compounds.

Below are some chapter questions, which students can go through and understand some of the related terms and topics that are given in this chapter.

Question 1: Define i. Diffusion ii. Evaporation iii. Boiling iv. Humidity

Answer:

i. Diffusion is the physical process involving the net movement of molecules from a region of higher concentration to lower concentration.

Ii. Evaporation is one of the types of vaporisation, where liquids change to a gaseous state. It occurs at the surface of liquids.

Iii. Boiling is a type of rapid vaporisation of a liquid. It occurs when a liquid reaches its boiling point.

Iv. Humidity is the amount of water vapour present in the air.

Question 2: What happens when water solidifies to ice?

a) Heat is liberated b) Heat is absorbed c) There is no change d) Depends on the condition if heat is absorbed or liberated.

Answer: a. Heat is liberated.

Question 3: What is a melting point?

Answer: The solid melts and changes into liquid at a certain temperature. The temperature at which a solid melts to become a liquid is called the ‘melting point’.

Question 4: Changes in ____, _______ and______ effect rates of evaporation

Answer: temperature, surface area and wind speed.

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