HOTS Questions: Matter in our Surroundings

# HOTS Questions: Matter in our Surroundings - Class 9

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## 30 Questions MCQ Test Science Class 9 - HOTS Questions: Matter in our Surroundings

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HOTS Questions: Matter in our Surroundings - Question 1

### Which of the following has the strongest interparticle force at the room temperature?

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 1

Higher the melting point of a substance, greater will be the force of attraction between particles. The melting point of iron is considerably high, so the force of attraction between its particles is higher.

HOTS Questions: Matter in our Surroundings - Question 2

### What is volume of gases?

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 2

A gas is a substance with no definite volume and no definite shape. Solids and liquids have volumes that do not change easily. A gas, on the other hand, has a volume that changes to match the volume of its container. The molecules in a gas are very far apart compared with the molecules in a solid or a liquid.

HOTS Questions: Matter in our Surroundings - Question 3

### The change of state from solid to liquid known as –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 3

The change of state from solid to liquid is known as Melting. This is a process in which a solid substance changes into a liquid on heating. Heat energy is required to break the bonds between molecules, allowing them to move around freely. This process is also known as fusion, and the amount of energy required is called the latent heat of fusion. In a phase diagram such as Figure 12.4.1, the melting point is the temperature at which a substance can transition from a solid to a liquid.

HOTS Questions: Matter in our Surroundings - Question 4

Dry ice is –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 4

Dry ice, sometimes referred to as "cardice", is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue.

HOTS Questions: Matter in our Surroundings - Question 5

The boiling point of water on kelvin scale is –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 5

Formula to change the value of celsius into kelvin is K = C + 273. As we know that boiling point of water is 100 c. SO, K = 100 + 273 K = 373 k.

HOTS Questions: Matter in our Surroundings - Question 6

The process of change of a liquid into vapour at any temperature is called –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 6

The process of conversion of a substance from the liquid state to its vapor state at any temperature below boiling point is called evaporation or vaporization.

HOTS Questions: Matter in our Surroundings - Question 7

Which factor affecting Evaporation -

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 7

The turning of any liquid into vapour is called Evaporation. The factors affecting the evaporation are:

1. Temperature. As the temperature increases, the rate of evaporation also increases.

2. Surface Area. As the Surface area increases, the rate of evaporation increases.

HOTS Questions: Matter in our Surroundings - Question 8

On increasing the temperature of the liquid the rate of evaporation is –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 8

The higher the temperature of liquid, the faster the rate of evaporation. This is due to the fact that as the liquid's temperature increase, the molecule of the liquid move about faster, thus increasing the rate of evaporation.

HOTS Questions: Matter in our Surroundings - Question 9

Fluids are –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 9

A fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas, and to some extent, plastic solids.

HOTS Questions: Matter in our Surroundings - Question 10

Which substance undergo sublimation process –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 10

Naphthalene because it changes from solid to gaseous without undergoing liquid as it is a sublime substance.

HOTS Questions: Matter in our Surroundings - Question 11

Condensation process is –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 11

The process of changing from gaseous state to liquid state on cooling is called condensation. On cooling the kinetic energy of particles decreases and intermolecular forces of attraction increases therefore gas converted into liquid.

HOTS Questions: Matter in our Surroundings - Question 12

The temperature at which liquid starts boiling at atmospheric pressure known as –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 12

When a liquid is heated, it eventually reaches a temperature at which the vapor pressure is large enough that bubbles form inside the body of the liquid. This temperature is called the boiling point

HOTS Questions: Matter in our Surroundings - Question 13

The melting point of ice is –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 13

The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. For ice, the melting point is 0°C at which ice a solid turn to water.

HOTS Questions: Matter in our Surroundings - Question 14

The physical state of matter which can be easily compressed –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 14

In gases, the atoms are much more spread out than in solids or liquids, and the atoms collide randomly with one another. A gas will fill any container, but if the container is not sealed, the gas will escape. Gas can be compressed much more easily than a liquid or solid.

HOTS Questions: Matter in our Surroundings - Question 15

Name the process by which a drop of ink spreads in a beaker of water –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 15

A drop of ink spreads in a beaker of water through diffusion. This is because the particles in liquids can move around each other, which means that eventually they are evenly mixed. Diffusion is the process of a substance spreading out to evenly fill its container or environment. In a solution, a concentrated solute diffuses to spread evenly in its solvent. concentration to low concentration.

HOTS Questions: Matter in our Surroundings - Question 16

The temperature at which a solid changes into liquid at atmospheric pressure is called –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 16

When a solid is heated, the particles are given more energy and start to vibrate faster. At a certain temperature, the particles vibrate so much that their ordered structure breaks down. At this point the solid melts into liquid. The temperature at which this change from solid to liquid happens is called the melting point. Each solid has a set melting point at normal air pressure. At lower air pressure, such as up a mountain, the melting point lowers.

HOTS Questions: Matter in our Surroundings - Question 17

Convert the temperature of 373°C to the kelvin scale ?

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 17

We know that ,K = °C + 273.15
= 373 deg C + 273.15 deg C
= 646.15 deg C

HOTS Questions: Matter in our Surroundings - Question 18

Convert the temperature of 270 K to the celsius scale –

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 18

We know that °C = K - 273.15

C= K - 273
C= 270 - 273
C = -3

HOTS Questions: Matter in our Surroundings - Question 19

Plasma is the.......... state of matter

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 19

A plasma is a hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons. The characteristics of plasmas are significantly different from those of ordinary neutral gases so that plasmas are considered a distinct "fourth state of matter."

HOTS Questions: Matter in our Surroundings - Question 20

The process for the change of a solid directly into its vapour is called

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 20

Sublimation is the process through which the solid substance changes directly into vapours or gaseous state without passing through liquid state. Dry ice is a common example of this process.

HOTS Questions: Matter in our Surroundings - Question 21

Under which of the following conditions we can boil water at room temperature?

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 21

At low pressure

Explanation: Boiling occurs when the vapor pressure of a liquid equals the external pressure. At lower pressures, the boiling point of water decreases. So, if the external pressure is reduced significantly (below atmospheric pressure), water can boil at room temperature. This phenomenon can be observed in a vacuum chamber, where the pressure is significantly reduced, allowing water to boil at room temperature.

HOTS Questions: Matter in our Surroundings - Question 22

Gases have highest rate of diffusion among all the three states of matter.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 22

Diffusion is the property of matter which is based on the motion of its particles. Diffusion occurs in gases, liquids and solids. Diffusion is fastest in gases and slowest in solids. The rate of diffusion increases on increasing the temperature of the diffusing substance.

HOTS Questions: Matter in our Surroundings - Question 23

Evaporation causes heating

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 23

Evaporation causes cooling because the process requires heat energy. The energy is taken away by the molecules when they convert from liquid into gas, and this causes cooling on the original surface.

HOTS Questions: Matter in our Surroundings - Question 24

Camphor changes to gaseous state without changing into liquid.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 24

It's true because camphor is sublime and it changes directly into gas without passing through the state of liquid. The process in which solid directly changes into gas without passing through the state of liquid is called sublimation.

HOTS Questions: Matter in our Surroundings - Question 25

Water has boiling point equal to 100°C.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 25

Boiling Point: The temperature at which the liquid boils and changes into gaseous state at the atmospheric pressure is called boiling point. For example, water boils at 100°C to form water vapour (at 76 cm pressure).

HOTS Questions: Matter in our Surroundings - Question 26

Evaporation is a bulk phenomenon

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 26

It is not bulk phenomenon because in this process liquid is not evapourated at same time .It takes time to evapourate whole liquid. Bulk means process that envolve molecules of both surface and inside part.

HOTS Questions: Matter in our Surroundings - Question 27

Intermolecular forces are maximum in solids and minimum in gases.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 27

Intermolecular force refers to the force that exists between two or more molecules.

Intermolecular force of attraction is maximum in solids

This is because molecules in solid remain very close to each other which allot a definite shape to the objects that are solid.

It is lesser in liquids and least in the gases.

HOTS Questions: Matter in our Surroundings - Question 28

Condensing is opposite to evaporating and freezing is opposite to melting.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 28

Evapouration is the process by which water turns to water vapour and condensation from vapours to water. So evapouration is opposite of condensation freezing is the process by which water turns to ice and melting is ice to water.so freezing is opposite of melting as both of them are true, Option A is correct!

HOTS Questions: Matter in our Surroundings - Question 29

The large volumes of gases can be put into small volumes of cylinders because of their property known as compressibility.

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 29

The large volumes of gases can be put into small volumes of cylinders because of their property known as compressibility. This is possible because of the large inter particle distance and weak force of attraction between the particles of gas.

HOTS Questions: Matter in our Surroundings - Question 30

Kinetic energy of molecules is directly proportional to

Detailed Solution for HOTS Questions: Matter in our Surroundings - Question 30

The kinetic energy of molecules
K = 3/2 kB. T
K = average kinetic energy per molecule of gas (J)
kB = Boltzmann's constant ()
T = temperature (k)

1. The kinetic energy of the molecules of a substance can be defined as the average energy associated with the molecule due to its vibrational motion.
2. Kinetic energy of the molecules is directly proportional to the temperature.
3. Increasing temperature increases the speed of vibration and hence the kinetic energy too and vice-versa.

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