NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

NCERT Solutions for Class 9 Science Matter in our Surroundings part 1 Class 9 Science book solutions are available in PDF format for free download. These ncert book chapter wise questions and answers are very helpful for CBSE exam. CBSE recommends NCERT books and most of the questions in CBSE exam are asked from NCERT text books. Class 9 Science chapter wise NCERT solution for Science Book for all the chapters can be downloaded from our website and myCBSEguide mobile app for free.

NCERT solutions for Science Matter in our Surroundings Download as PDF

NCERT Class 9 Science Chapter wise Solutions

• 01 –  Matter in Our Surroundings
• 02 – Is Mattter Around us Pure
• 03 – Atoms and Molecules
• 04 – Structure of the Atom
• 05 – The Fundamental Unit of Life
• 06 – Tissues
• 07 – Diversity in Living Organisms
• 08 – Motion
• 09 – Force and Laws of Motion
• 10 – Gravitation
• 11 – Word and Energy
• 12 – Sound
• 13 – Why Do We Fall Ill
• 14 – Natural Resources
• 15 – Improvement in Food Resources

NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

1. Which of the following are matter?

Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.

Ans. Chair, air, smell, almonds, cold drink and smell of perfume are matter.

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2. Give reasons for the following observation:

The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.

Ans. Since hot sizzling food has temperature higher than cold food and at higher temperature diffusion rate (movement) of particles is very fast due to this the smell of hot sizzling reaches us from several metres away.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

Ans. If diver has ability to cut through water in a swimming pool then it shows that the particles of matter have a kind of force working between them. Because of this force the particles of matter remain together till some external force is applied.

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4. What are the characteristics of the particles of matter?

Ans. The characteristics of particles of matter are as follows:

i) particles of matter have gap between them.

ii) particles of matter are in continuous motion

iii) particles of matter have an attraction force between them to keep them together.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

1. The mass per unit volume of a substance is called density.

(density = mass/volume).

Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water, chalk, cotton and iron.

Ans. Arranging substances in their increasing order of densities:

Air< exhaust from chimneys< cotton< water< honey< chalk< iron.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

2. (a) Tabulate the differences in the characteristics of states of matter.

(b) Comment upon the following:

rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Ans. (a)

(b) Rigidity→ It is the property of matter to maintain its shape even if external forces work and the solids show this property.

Compressibility → It is the property of matter to allow compression under high pressure and the gases show this property.

Fluidity → It is the property of a substance to easily flow and allow change in its shape under external forces and this property is exhibited by both liquids and gases.

Filling a gas container → Gases can be compressed easily hence they can be filled within a vessel at high pressure. This property of gases allows their convenient filling into a small container or cylinder and that also in a large volume. It also allows their easy transport from one place to the other e.g. CNG.

Shape→ According to the type of matter shape differs depending upon location of particles like Solids have definite shape while Liquids acquire the shape of their container and gases as such don’t have any shape.

Kinetic energy → It is the kind of energy present in an object when it is under motion as the particles of that object/matter are continuously moving therefore matter has kinetic energy. However greater is the movement more will be the kinetic energy and vice a versa i.e. solid < liquid < gas

Density → Mass per unit volume of a substance/matter is known as its density i.e. density = mass/volume

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

3. Give reasons

(a) A gas fills completely the vessel in which it is kept.

(b) A gas exerts pressure on the walls of the container.

(c) A wooden table should be called a solid.

(d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

Ans.(a) Since the attraction force between particles of a gas is negligible i.e. extremely less hence particles freely move/flow in all possible directions as a result gas fills completely the vessel in which it is kept.

(b) Freely moving particles of gas hit the walls of its container continuously and randomly therefore such random and erratic motion of gas particles exerts pressure on the walls of the container.

(c) A wooden table particles are quite rigid, have a fixed location and also possess a definite shape and volume. Due to all these properties we should call a wooden table a solid substance.

(d) Air is a mixture of gases and since particles of gas are far apart so same is true for air therefore we can easily move our hand in air. But a solid block of wood is hard and rigid that resists any change in location of its particles hence we need a karate expert in case of a solid block of wood.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

4. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

Ans. Ice represents solid state of water. If we observe its 3D structure, a large empty space is found inside ice as a result it becomes less in weight as compared to water. Due to its specific structure though solid, ice floats on water.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

1. Convert the following temperature to Celsius scale:

i) 300 K

ii)573 K

Ans. i)

ii)

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

2. What is the physical state of water at:

a.

b.

Ans.is the boiling point of water hence at both the temperatures water is in gaseous state i.e. water vapour.

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3. For any substance, why does the temperature remain constant during the change of state?

Ans. During the change of state the heat or energy provided to particles of matter is utilized to take the particles of matter apart from each other as a result the temperature of substance or matter remains constant during change of state.

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4. Suggest a method to liquefy atmospheric gases.

Ans. If we decrease temperature and increasing pressure we can liquefy the atmospheric gases.

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NCERT Solutions for Class 9 Science Matter in our Surroundings part 1

1. Why does a desert cooler cool better on a hot dry day?

Ans. On a hot dry day rate of evaporation is faster. In a desert cooler when exhaust fan is on, hot air enters through the straw mates and at this site evaporation of water takes place and that also at faster rate. It takes away heat from air so the air becomes cool even cooler on a hot dry day.

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2. How does the water kept in an earthen pot (matka) become cool during summer?

Ans. During summers the water present on the surface of the earthen pot evaporates which causes the cooling effect. Besides earthen pot bears pores on it hence evaporation occurs continuously so is cooling.

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3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Ans. Some liquids get quickly vaporized and they are called volatile liquids. Acetone, petrol and perfume are also volatile liquids therefore they get heat from our palm and cause cooling.

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4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Ans. Saucer has a bigger surface area as compared to cup. Since evaporation is a surface phenomenon, by using a saucer instead of cup we are increasing the surface are for evaporation to occur. Faster evaporation of particles of tea or milk allows cooling and taking a sip becomes easier.

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5. What type of clothes should we wear in summer?

Ans. Cotton is a good absorb ant of water hence it absorbs sweat quite well and pores in the fabric expose that sweat to easy evaporation hence we should prefer wearing cotton clothes in summer.

NCERT Solutions for Class 9 Science

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