Ncert solution class 9 science ch 1 matter in our surrounding.


Get the NCERT solution for class 9 science chapter 1. 



These NCERT solutions for science 9 classes in our environment provided in the NCERT Book Chapter 1 - In the case of the detailed answers to all the questions which are prescribed for class 9 in schools.
science book
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questions 1 to 4.

Q 1. Which of the following are matter?
 ..
Answer: chair, air ,almonds and cold drinks.

Q 2.Give reasons for the following observation: 
Answer: The solid spreads at very slow rates. But, if the temperature of the concrete increases, the rate of dissemination of solid particles in the air increases. This is due to the increase in the dynamic energy of solid particles. Therefore, the smell of warm roasted food reaches us even at a distance, but to get the odor from cold food, we have to go closer.

Q 3. Adiver is able tocut through water in a swimming pool.
Which property of matter does this observation show?
AnswerThe ability of a diver to cut through water in a swimming pool shows that the substance is made of particles.

Q 4. What are the characteristics of particles of matter?
AnswerThe features of particles of matter are:
(i) The particles in the substance have spaces between them.
(ii) particles of matter are constantly running.
(iii) Matter particles attract each other.

 questions 1 to 4.


Q1. Themass perunit volume of a substance is called density (density = mass/volume). 
Arrange the following in order of increasing density − air, exhaust from chimney, honey, water, chalk, cotton, and iron.
AnswerThe given substances can be shown in the increasing order of their density:
Air <Exaust from chimney <Cotton <Water <Honey <Chalk < Iron

Q 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.
Answer: (a) by self
(b) Hardness can be expressed in the form of material tendency to resist change in shape. Compression is the ability to reduce in small amounts when force is applied. Liquidity is the ability to flow. By filling the gas container, we mean the receiver of the container size by the gas.

The size defines a certain extent.

Kinetic energy is the energy received by a particle due to its speed.

Density is per unit volume mass.

Q 3. Give reason.
Answer(a) There is little attraction between gas particles. Thus, gas particles move fast in all directions. Therefore, the gas completely fills that vessel in which it is kept.

(b) The particles of gas are transferred randomly in all directions at high speeds. As a result, the division hit each other and hit it on the container walls with a force. Therefore, the gas puts pressure on the container's walls.

(c) There is a certain size and amount of a wooden table. It is very harsh and can not be compressed, that is, it has the characteristics of concrete. Therefore, a wooden table should be called solid.

(d) There are large spaces between particles of air. On the other hand, there is a small space between wood particles. Apart from this, it is rude. For this reason, we can easily move our hands in the air, but to do this through the solid concrete block, we need a karate specialist.

Q 4. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why?
AnswerThe unit mass per substance is called density (density = mass / quantity). Since the amount of substances increases, its density decreases. Although the snow is a solid, but there are a large number of empty spaces between its particles. These spaces are larger in comparison to the spaces between water particles. Thus, the amount of ice is more than water. Therefore, the density of ice is less than water. Water less than density can float on water. Therefore, snow floats on the water.

 


questions 1 to 4.



Q 1. Convert the temperature to Celsius scale:
(a) 300k
(b) 573k
Answer:(a) 300 K
 = (300 − 273)°C = 27°C
(b)573 K
 = (573 − 273)°C = 300°C

Q 2. What is the physical state of water at.
(a)250°c
(b)100°c
Answer:(a) 250 ° C water is present in the gaseous state.
(b) At 100 degree Celsius, the water can be present in both liquid and gaseous form. At this temperature, after getting heat equal to the latent heat of evaporation, the water starts to change from the liquid state to the gaseous state.

Q 3. For any substance, why does the temperature remain constant during the change of state?
AnswerDuring the state's transformation, the temperature remains constant. This is because all the heat supplied to increase the temperature is used to change the state by controlling the forces of attraction between the particles. Therefore, it does not contribute to the increase in temperature of heat content.

Q 4Suggest a method to liquefy atmospheric gases.
AnswerBy applying pressure and reducing temperature, atmospheric gases can be liquified.


questions 1 to 5.



Q 1. Why does a desert cooler cool better on a hot dry day?
AnswerWhen a liquid evaporation occurs, the particles of the liquid absorb energy from the ambient environment to compensate for the loss of energy during evaporation. It makes the surrounding cool In a desert cooler, the water inside it is made for evaporation. From this, the energy is absorbed by the environment, so the environment is cooled down. Again, we know that evaporation depends on the amount of water vapor present in air (humidity). If the amount of water vapor present in the air is low, then the evaporation is high. On hot dry days, the amount of water vapor present in the air is low. Thus, the water inside the desert cooler is evaporated so that the surrounding environment is cooled down. This is the reason that a desert cooler is cooler on a hot dry day.

Q 2. How does water kept in an earthen pot (matka) become cool during summers?
AnswerThere are some holes in the pottery through which the liquid is evaporated inside the vessel. This vaporization cools the water inside the pot. In this way, the water kept in the pottery during the summer gets cooled.

Q 3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Answer: When we put some acetone or petrol or perfume on our palm, it becomes evaporated. During evaporation, the particles absorb the energy to damage the energy to damage energy from the surrounding or palm surfaces, causing the atmosphere to cool down. Therefore, when we put some acetone or petrol or perfume then our palm seems cold.

Q 4. Why are we able to sip hot tea or milk faster from a saucer than a cup?
AnswerCompared to a liquid in one cup, a liquid contains a liquid. Thus, it is rapidly evaporated in a soccer compared to a cup and becomes faster cooler. For this reason, we can immerse the hot tea or milk faster than a cup with a soccer.

Q 5. What type of clothes should we wear in summers?
Answer: We should wear cotton clothes in summer. During the summer, we sweat more. On the other hand, cotton is a good absorber of water. Thus, it absorbs sweating from our body and rapidly exposes vaporization to the atmosphere. During this vaporization, the liquid gain from the surface of our body cools the particles on the surface of energy.

Exercise:


Q 1. Convert the temperature to Celsius scale.
(a) 300K
(b) 573K
Answer:(a) 300K 
= (300 − 273)°C = 27°C
(b) 573K
 = (573 − 273)°C = 300°C

Q 2Convert the  temperatures to Kelvin scale.
(a) 25°C
(b) 373°C
Answer: (a) 25°C 
= (25 + 273) K = 298K
(b) 373°C
 = (373 + 273)K = 646K

Q 3. Give reason:
Answer: (a)Naphthalene easily undergoes regeneration ie, it takes place easily from the solid to the gas in the condition of naphthalene. Thus, the naphthalene balls disappear without any concrete release.

(b)Gaseous particles have high speed and large space among them. Perfume particles spread very fast in these gaseous particles and reach our nose. It enables us to smell the perfume from a distance.

Q 4. Arrange the following substances in increasing order of forces of attraction between particles:
 water, sugar, oxygen.
AnswerSugar is a solid; The strength of attraction between sugar particles is strong. Water is a liquid; Here the powers of attraction are weaker than sugar. Oxygen is a gas; The strength of attraction is the weakest in gases. Thus, the increasing order of the powers of attraction between particles of water, sugar and oxygen. oxygen <water <sugar

Q 5. What is the physical state of water at:
(a)25°C
(b)0°C
(c)100°C
Answer(a) Water is present at 25 degrees Celsius in liquid state.
(b) At 0 degree Celsius, the water can be present in both solid and liquid form. At this temperature, after obtaining heat equal to the latent heat of fusion, the solid form of water i.e. ice turns into its liquid form, i.e. water
(c) At 100 ° C, the water can be present in both liquid and gas form. At this temperature, after receiving heat equal to the latent heat of evaporation, the water starts changing from its liquid state to its gaseous state, i.e., water vapor.

 Q 6. Give reason to justify:-

Answer: (a)At room temperature (25 degrees Celsius), water is a liquid because it has the following characteristics of liquid:
(i) At room temperature, there is no size of water, but there is a certain amount in it, in which it is the size of the container in which it is placed.
(ii) At room temperature, water flows.
(b) A iron almirah is a solid at room temperature (25 degrees Celsius) because:
(i) It has a solid size and amount at room temperature.
(ii) It is rigid as a solid at room temperature.

Q 7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Answer273 ice has less energy than ice (although both are at the same temperature). There is an extra latent heat of fusion in water. Therefore, on 273, ice is more effective in cooling with water.

Q 8. What produces more severe burns, boiling water or steam?
AnswerBoiling water has more energy in steam than steam. It has the extra latent heat of evaporation. Therefore, irritation produced by steam is more serious than the boiling water produced.


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