Important Questions (1 mark): Matter in our Surroundings

# Important Questions (1 mark): Matter in our Surroundings - Class 9

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## 25 Questions MCQ Test Science Class 9 - Important Questions (1 mark): Matter in our Surroundings

Important Questions (1 mark): Matter in our Surroundings for Class 9 2023 is part of Science Class 9 preparation. The Important Questions (1 mark): Matter in our Surroundings questions and answers have been prepared according to the Class 9 exam syllabus.The Important Questions (1 mark): Matter in our Surroundings MCQs are made for Class 9 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Important Questions (1 mark): Matter in our Surroundings below.
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Important Questions (1 mark): Matter in our Surroundings - Question 1

### The room temperature on Celsius scale is 25°C. What is the temperature on the Kelvin scale?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 1

K = °C + 273,

25°C = 273 + 25 = 298K.

So, temperature of 25°C is equal to 298K.

Important Questions (1 mark): Matter in our Surroundings - Question 2

### The melting points of two solids [A] and [B] are 300K and 350K respectively. Which has more inter-particles forces?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 2

With increase in temperature, inter-particles forces decreases. As the melting point of solid A is less than Solid B. Solid B has more inter-particle forces of attraction. Higher the melting point more the inter-particle force.

Important Questions (1 mark): Matter in our Surroundings - Question 3

### Which of the following is not endothermic process?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 3

An endothermic process is any process which requires or absorbs energy from its surroundings, usually in the form of heat. It may be a chemical process, such as dissolving ammonium nitrate in water, or a physical process, such as the melting of ice cubes. Insoluble heavy impurities involve the opposite of an endothermic process which is exothermic process one that absorbs energy in the form of heat.

Important Questions (1 mark): Matter in our Surroundings - Question 4

The two major gases present in air are

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 4

Air is a mixture of gases. Two main constituent of air are Oxygen (21%) and Nitrogen (78%). Other gases includes carbon dioxide, helium, water vapour etc.

Important Questions (1 mark): Matter in our Surroundings - Question 5

Statement A: In Kelvin temperature, the symbol () is not used.
Statement B: Mercury is used in glass thermometers because it does not stick with glass.

Which of the two statements is true?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 5

In Kelvin temperature, the symbol () is not used. Mercury is used in glass thermometers because it does not stick with glass and have shiny surface to viewed easily.

Important Questions (1 mark): Matter in our Surroundings - Question 6

Match the following with correct response.

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 6

solid carbon dioxide is known as dry ice. The reduced evaporation is called humidity. Evaporation is increased by temperature. The liquefied gas increases pressure and reduces temperature.

Important Questions (1 mark): Matter in our Surroundings - Question 7

Which of the following solids undergo sublimation upon heating?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 7

The process of changing solid directly into gases without changing into liquid is called sublimation. In the substance given above only Iodine is a sublime substance.

Important Questions (1 mark): Matter in our Surroundings - Question 8

Which of the following is not a compound?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 8

Brass is a homogeneous mixture of copper and zinc.

Important Questions (1 mark): Matter in our Surroundings - Question 9

Name one common substance which can undergo a change in state upon heating or cooling.

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 9

Water can undergo a change in state upon heating and cooling. On heating above 1000C water change into gaseous state and on cooling below 00C it changes into solid state.

Important Questions (1 mark): Matter in our Surroundings - Question 10

Rate of diffusion is the fastest in

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 10

Rate of diffusion in gases is high because they have large intermolecular space and they possess more kinetic energy than liquids and gases.

Important Questions (1 mark): Matter in our Surroundings - Question 11

When the liquid starts boiling, the further heat energy which is supplied

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 11

When the liquid starts boiling, the further heat energy which is supplied is absorbed as latent heat of vaporization by the liquid to change its state of matter.

Important Questions (1 mark): Matter in our Surroundings - Question 12

Sulphur dioxide is collected in the lab in a gas jar by upward displacement of air. Which of the following statement is correct regarding the density of the gas?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 12

At room temperature, sulfur dioxide is a nonflammable, colorless gas that is heavier than air. Its strong, pungent odor and irritating properties usually provide adequate warning of its presence.

Important Questions (1 mark): Matter in our Surroundings - Question 13

Pressure on the surface of a gas is increased. What will happen to the inter-particle forces?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 13

When the pressure on the surface of a gas is increased. The particles of gases comes closer that increase the inter-particle force of attraction.

Important Questions (1 mark): Matter in our Surroundings - Question 14

What are the characteristics of the particles of matter?
A. Particles of matter are in continuous motion
B. Particles of matters do not have spaces between them
C. Particles of matter attract each other
D. Particles of matter are very large in size

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 14

The characteristics of particles of matter are as follows:

1. Particles of matter have space between them

When we dissolve salt in water, it is observed that the particles of salt get evenly distributed in water. Also, it is observed that the presence of salt particles did not change the level of water in the beaker. This could be possible only if the particles of salt were accommodated in between the water particles. Thus, this clearly proves that space exists between water particles.

2. Particles of matter are in continuous motion

We know that there is a lot of space present between the particles of matter. Particles of matter are never at rest and keep moving continuously in these free spaces. The particles of matter move continuously and their speed increases with an increase in temperature.

3. Particles of matter attract each other

The particles of matter attract each other. However, this force of attraction varies from matter to matter.

Important Questions (1 mark): Matter in our Surroundings - Question 15

Statement A: Evaporation is a surface phenomenon but boiling is not.
Statement B: The diffusion of the gases varies inversely as the square root of their densities.

Which of the two statements is true?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 15

Evaporation is a surface phenomenon as takes place only on the surface of liquid but boiling is a bulk phenomenon. The rate of diffusion of gases varies inversely as the square root of their densities.

Important Questions (1 mark): Matter in our Surroundings - Question 16

Statement A: The temperature of the liquid becomes constant once it starts boiling
Statement B: Pressure of air at sea level is 70cm

Which of the two statements is true?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 16

The temperature of the liquid becomes constant once it starts boiling. The heat is used to change the state of matter. The pressure of air at the sea level is 760mm of Hg. So, statement A is correct only.

Important Questions (1 mark): Matter in our Surroundings - Question 17

In which one of the following sets is each one a solid under ordinary conditions-

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 17

In the different sets of substance given above, salt, sugar and chalk are solid under ordinary temperature. As Mercury, water and oxygen and nitrogen are not solid.

Important Questions (1 mark): Matter in our Surroundings - Question 18

A substance upon heating directly changes into gaseous state. What is this change called?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 18

The process of changing solids into gases without changing into liquid state or gases directly into solid is called sublimation.

Important Questions (1 mark): Matter in our Surroundings - Question 19

Which of the following is needed by surgeons during surgery?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 19

Before its development as a surgical anesthetic, ether was used throughout the history of medicine, including as a treatment for ailments such as scurvy or pulmonary inflammation. A pleasant-smelling, colorless and highly flammable liquid, ether can be vaporized into a gas that numbs pain but leaves patients conscious.

Important Questions (1 mark): Matter in our Surroundings - Question 20

Name a process by which an impure sample of naphthalene can be purified.

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 20

Impure sample of naphthalene can be purified by sublimation process. During this process, naphthalene being sublime changes into vapours leaving behind impurities. Vapour can be cooled by condensation.

Important Questions (1 mark): Matter in our Surroundings - Question 21

A gas can be best liquefied

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 21

State of matter can be changed by changing temperature and pressure. A gas can be liquefied by increasing the pressure and reducing the temperature to brings the particle close to each other.

Important Questions (1 mark): Matter in our Surroundings - Question 22

A liquid is kept in an open china dish. A The evaporation of the liquid can be accelerated

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 22

A liquid is kept in an open china dish. The evaporation of the liquid can be accelerated by keeping the dish in the open, by blowing air into the liquid or by keeping the dish under a running fan. Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance.

Important Questions (1 mark): Matter in our Surroundings - Question 23

The evaporation of a liquid occur only at

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 23

The process of changing liquid into gases from its upper surface at all temperature is called evaporation. Rate of evaporation increase with increase in temperature, surface area and wind speed.

Important Questions (1 mark): Matter in our Surroundings - Question 24

Which of the following is not a chemical reaction?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 24

Boiling is a physical process. When boiling takes place, particles in the substance vibrate more and of weak intermolecular bonds are broken in order for the substance being heated to move into the gaseous phase. Covalent bonds are not broken when boiling occurs. This means that no chemical reaction has taken place. The ratio in which the atoms are bonded together in a substance remains constant.

Important Questions (1 mark): Matter in our Surroundings - Question 25

Which of the following is the nuclear fuel in the sun?

Detailed Solution for Important Questions (1 mark): Matter in our Surroundings - Question 25

Hydrogen as a fuel in Sun. The source of Sun's incessant energy is hydrogen which is continuously converting to helium through nuclear fusion reaction releasing energy.

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