Question1 : Which of the following characteristic is false for matter.
(A) It occupies space.(B) It has mass.
(C) It has inertia
(D) It is least effected by gravity
Explanation: Gravitational force do not any effect on the particles of matter.
Question2 : In which of the given combinations would the rate of diffusion would be slowest?
(A) Between two different gases(B) Berween two different liquids
(C) Between a liquid and a solid
(D) Between two solids
Explanation: Diffusion process is the slowest in solids, as compared liquids and gases.
Question3 :In Which of the following ,Intermolecular force is very weak.
(B) Steam
(C) Milk
(D) Sugar crystal
Explanation:
Intermolecular force is very weak in gasous state of matter.
Question 4 : The temperature at which the vapour pressure of any liquid becomes equal to atmospheric pressure is known as __.
(B) Melting Point
(C) Freezing Point
(D) Triple Point
Explanation:
At boiling Point the water is converted into vapour.
Question 5 : What do you understand by fussion?
(B) Converting liquid into solid
(C) Converting liquid to gas
(D) Inter-converstion of gas into solid
Explanation:
Fussion means melting, And in this process solid is coverted into liquid.
Question 6 : How can the evaporation of liquids can be increased?
(B) By contracting the surface area
(C) By increasing the temperature
(D) All of these
Explanation:
If the temperature is increased then rate of evaporation will also increase.
Question 7 : What is the correct order of evaporation?
(B) Petrol > Kerosene > Water > Alcohol
(C) Alcohol > Petrol > Kerosene > Water
(D) Petrol > Alcohol > Kerosene > Water
Explanation:
Alcohol evaporates very fast, then comes petrol, then kerosene and At last Water.
Question 8 : The major constitutent of cooking gas is ____ ?
(B) Propane
(C) Butane
(D) Methane
Explanation:
The cooking gas we use at home is mainly made up of butane.
Question 9 : We have often seen the naphthalene balls that we put in our clothes disappear after some time. What could be the phenomena ?
(B) Sublimation
(C) Diffusion
(D) Contraction
Explanation:
The process by which object turns from solid into direclty into gaseous state is called as sublimation. Some example of this phenomenon are campour, naphthalene balls etc..
Question 10 : What happens to the temperature when a solid melts ?
(B) It decreases
(C) It remains same
(D) First increased then decreases
Explanation:
The heat given to solid the change into liquid is called latent heat, during this process when heat is provided it is utilized into the converstion of solid into liquid. It doesn’t increase the temperature of the solid.
Question 11 : In condensation, there is ___
(B) Gain of energy
(C) Neither Gain or Loss of energy
(D) Lossof energy in beginning followingby gain.
Explanation:
Condensation is the reverse process of Evaporation, in Evaporation the process the energy is given out and whereas in Condensation energy is gained.
Question 12 : For a state of matter to be liquid, which of the given conditions is true ?
(B) The boiling point of the substanceis above the room temperature at the atmospheric pressure.
(C) The boiling point of the substance i below the room temperature at the atmospheric pressure.
(D) None of these
Explanation:
If the substance is liquid at room temperature, that means that the boiling point of the substance is above the room temperature and the melting point is below the room temperature.
Question 13 : We can often see large volume of gases in small cylinders. How is this possible
(B) Gases can solidify
(C) Gases can be evaporated
(D) Gases can be compress
Explanation:
Gases can be compressed easily and can even come in small cylinder easily.
Question 14 : On converting 25°C, 38°C and 66°C to kelvin scale, the correct sequence of temperature will be
(B) 298 K, 300 K and 338 K
(C) 273 K, 278 K and 543 K
(D) 298 K, 310 K and 338 K
Explanation:
Formula for conversion °C into K=> °C+273=K
Question 15 :In all the three states of water, (i.e. ice, liquid and vapour) chemical composition of water
(B) remains same
(C) sometimes same and sometimes different
(D) none of the above
Explanation:
In all the three states of water, (i.e. ice, liquid and vapour) chemical composition of water remains same.
Question 16 : Which of the following statements is incorrect about the state of matter?
(B) Plasma consists of super energetic and super excited particles.
(C) The plasma glows with a special colour depending on the nature of the gas.
(D) Bose-Einstein condensate is formed by heating gas of extremely low density.
Explanation:
Bose-Einstein condensate is formed by cooling gas ( very close to absolute zero (−273°C)of extremely low density.
Question 17 : What willl happen if an inverted clyinder of hydrogen gas is placed upon a cylinder of nitrogen oxide?
(B) Both gases will move down
(C) Hydrogen will move down but nitrogen oxide will remains as it is
(D) Hydrogen will move down but nitrogen oxide will move upwards
Explanation: This process is called diffusion, where two more more substance(gases, liquidis and solids) merge with each other. Here in this process hydrogen will merge with nitrogen oxide.
Question 18 : What can you say about the particles of matter?
(B) These attract each other
(C) These have spaces between them
(D) All of these
Explanation: Any particle of matter are very small, they attract each other and they spaces between them.
Question 19 : Identify the odd one out taking state of matter into consideration:
(B) Lemonade
(C) A strached rubber band
(D) A metal block
Explanation: All the other substances are in solid and Lemonade is alone a liquid substance.
Question 20 : From the given options, which metal has the highest melting point?
(B) W (Tungsten)
(C) B (Boron)
(D) Cr (Chromium)
Explanation: The melting point of tungestion is 3,422 °C where iron has 1,538 °C, Born has 2,076 °C and Chromium has 1,907 °C.
Question 21 : Which of these is correct for diffusion?
(B) Diffusion only take place in gases.
(C) Diffusion does not take place in solids.
(D) Diffusion takes place in all the three states of matter, viz. solids, liquids, gases.
Explanation: Diffusion process takes place in all three states of matter. Solids very slow, liuids a bit fast and gases very fast.
Question 22 : How can gases be liquified
(B) Increase the pressure, lower the temperature
(C) Lower the pressure, increase the temperature
(D) Lower the pressure, Lower the temperature
Explanation: When pressure is increased then state of matter of the substances changes, and if we decrease the temperature it will not help in the expansion of the gas.
Question 23 : What is plasma?
(B) A type of gas
(C) Combiation of three states of matter
(D) None of these
Explanation: Plasma is the fouth state of matter.
Question 24 : IN which of the following conditions, the rate of evaporation will be low?
(B) Surface area is increased
(C) Increase the temperature of the liquid
(D) Desreased wind speed
Explanation: If the wind speed is decreased then rate of evaporation will also decrease.
Question 25 : Which state of matter will have maximum fluidity?
(B) Gases
(C) Both have equal fluidity.
(D) None of th two possess fludidity
Explanation: Gas particles are very far away from each other so they have low inter-molecular force and hence they they have high fluidity.
Question 26 : Which of the following will have highest inter-molecular force of attraction?
(B) H2O
(C) CO2
(D) Liquid ethyl alcohol
Explanation: Here dry ice is a solid, so solids have very high inter-molecuular force of attraction as their particles are tightly packed.
Question 27 : The state from vapour to liquid is known as ___________.
(B) Evaporation
(C) Diffusion
(D) Sublimation
Explanation: The state from vapour to liquid is known as Condensation.
Question 28 : What is conversion of solid state to liquid state known as?
(B) Diffusion
(C) Vaporization
(D) Sublimation
Explanation: Conversion of solid state to liquid state known as Fusion
Question 29 : Why does ice have cooling effects and steam has burning effects?
(B) Water molecules have high energy in ice and low energy in steam
(C) Both hace same molecular energy but ice take energy from body os has a cooling effect.
(D) None of these
Explanation: Water molecules have low kinetic energy in ice so has a coolig effect, and in steam the kinetic energy is very high so has a burning effect.
Question 30 : Who discovered the random movement of particles?
(B) Robert Brown
(C) Kanada
(D) None of these
Explanation: Robert Brown discovered the random movement of particles.
Question 31 : Why does alcohol exist in liquid stae at room temperature?
(A) It is highly compressible(B) Its melting point is below room temperature
(C) It posses strong intermolecular force.
(D) Both (B) and (C)
Explanation: Alcohol has melting point is below room temperature and posses strong intermolecular force.
Question 32 : The quantity of matter present in an object is called its:
(B)Gram
(C)Mass
(D)None of these
Explanation:
Amount of matter present in a object is called Mass.
Question 33 : The boiling point of alcohol is 78°C. What is this temperature in Kelvin scale:
(B) 378 K
(C) 351 K
(D) 251 K
Explanation:
use formula °C+273=K
Question 34 : In which of following phenomena water changes into water vapour below its boiling Point.?
(B) Condensation
(C) Boiling
(D) None of these
Explanation:
Evaporation happens when a liquid substance converted into gas below boiling point of liquid.
Question 35 : When potassium permagnet is put in water, the colourless water attains purple colour. What could be the possible reasons?
(i) The particles of water and potassium permagnet are in motion.
(ii) The process of diffusion is taking place.
(iii) The process of sublimation is taking place.
(iv) Only the particles of potassium permanganet are moving
(B) Option (i) and (ii)
(C) Option (i) and (iii)
(D)Only option (iv)
Explanation:
In this case, process of diffusion is taking place. The particles of water and potassium permagnet are in motion as well as The process of diffusion is taking place.
Question 36 : According to Robert Brown observation, which of the given statements is/are correct?
(i) The speed of paricles decrease with increase temperature
(ii) The speed of particles increase with increase with increase in temperature
(iii) The particles move in a linear motion.
(iv) The particles move in a zigzag motion.
(B) (i) and (iii)
(C) (ii) and (iii)
(D) (ii) and (iv)
Explanation:
According to Robert Brown observation, which of the given statements are:-
(i) The speed of particles increase with increase with increase in temperature
(ii) The particles move in a zigzag motion.
Question 37 : Which of the following will have a fixed volume?
(B) Only liquids
(C) Only gases
(D) Both solids and liquids
Explanation:
Solids have Fixed shape and volume and liquids have fixed volume not a fixed shape.
Question 38 : Latent heat of vaporization causes state change at which temperatuure
(B) 373K
(C) Bellow boiling point of liquid
(D) Both (A) and (B)
Explanation:
100°C is only 373K
Question 39 : Out of the given statements, which two statemanets are not true:
(i) Evaporation takes place at the surface of the liquids but boiling takes place throughout the mass of the liquid.
(ii) Evaporation is a rapid process, boiling is a slow process.
(iii) Evaporation takes place at constant temperature.
(iv) Boiling takes place at constant temperature.
(B) (ii) and (iii)
(C) (i) and (iii)
(D) (iii) ad (iv)
Explanation:
(ii) Evaporation is a slow process, boiling is a rapid process.
(iii) Evaporation takes place at all temperature.
Question 40 : Identify which of the following show evaporation:
(B) Sweating
(C) Drying of clothes
(D) All of these
Explanation:
In all the process above the process of evaporation takes place.
Question 41 : What can you say about plasma?
(i) It is a mixture of free electrons and ions
(ii) It contains only electrons
(iii) Iy can also be artificial
(B) Only (i) is correct
(C) (i) and (iii) are correct
(D) Only (ii) is corrct
Explanation:
Plasma is a mixture of free electrons and ions and it can be created artificially.
Question 42 : Choose the correct statement?s
(i) Gases have high densities
(ii) Liquids have high compressiblity
(iii) Solids have minimum kinetic energy of particles
(B) Only (ii)
(C) Only (iii)
(D) (i) and (iii)
Explanation:
Solids have minimum kinetic energy of particles.
Question 43 : The boiling point of water on Celsius and Kelvin scale respectively is:
(B) 0, 273
(C) 273, 373
(D) 100, 373
Explanation: Boiling point of water in celsius scale is 100°C, and in Kelvin scale it is 373K.
Question 44 : The liquid which has the highest rate of evaporation is:
(B) Nail- polish remover
(C) Water
(D) Alcohol
Explanation:
Nail-paint remover/spirit has the highest rate of evaporation amongst the given substances.
Question 45 : The state of matter which consists of super energetic particles in the form of ionized gases is called:
(B) Liquid state
(C) Bose- Einstein condensate
(D) Plasma state
Explanation:
Plasma is the fourth state of matter. Plasma has both non-charged and charged ions in it with very high kinetic energy particles.
Question 46 : The force that binds the particles of matter together is known as:
(B) Bond
(C) Intermolecular force
(D) Nuclear force
Explanation:
The force acting between two particles is called intermolecular force.
Question 47 : The change of a liquid into vapour is called:
(B) Solidification
(C) Sublimation
(D) None of these
Explanation:
The change of a liquid into vapour is called Vaporization
Question 48 : Which of the following describes the liquid phase?
(B) It has a definite shape but not a definite volume
(C) It has a definite volume but not a definite shape
(D) It has neither a definite shape nor a definite volume
Explanation:
Liquid has definite volume but not a definite shape as it takes the shape of container.
Question 49 : When a teaspoon of solid sugar is dissolved in a glass of liquid water, what phase or phases are present after mixing:
(B) Still solid and liquid
(C) Solid only
(D) None of these
Explanation:
As after disolving their is no such left lest and only liquid is remaining.
Question 50 : Volume of a gas at a particular temperature and on atmospheric pressure is 200 ml. Keeping the temperature constant if pressure is increased to 5 atmosphere, then volume of the gas will be:
(B) 40 ml
(C) 200 ml
(D) 205 ml
Explanation:
BY byoul's formula:-
P1V1=P2V2
=> 200*1=x*5 => x = 200/5 => x = 40
Question 51 : Which of the following statements best explains why a closed balloon filled with helium gas rises in air?
(B) The average speed of helium atoms is higher than the average speeds of air molecules, and the higher speed of collisions with the balloon walls propels the balloon upward.
(C) Because the helium atoms are of lower mass than the average is molecules, the helium gas is less dense than air. The balloon thus weighs less than the air displaces by its volume.
(D)Because helium has a lower molar mass than the average air molecules, the helium atoms are in faster motion. This means that the temperature. Hot gases tend to rise.
Explanation:
Balloon filled with helium gas rises in air because the helium atoms are of lower mass than the average is molecules, the helium gas is less dense than air. The balloon thus weighs less than the air displaces by its volume.
Question 52 : Non- reacting gases have a tendency to mix with each other. This phenomenon is known as:
(B) Diffusion
(C) Effusion
(D) Explosion
Explanation:
Non- reacting gases have a tendency to mix with each other. This phenomenon is known as Diffusion.
Question 53 : A gas which obeys the gas laws is known as:
(B) A heavier gas
(C) A lighter gas
(D) A real gas
Explanation:
A gas which obeys the gas laws is known as An ideal gas.
Question 54. What term is used to describe the phase change of a solid to a liquid?
(b)Melting
(c)Boiling
(d)None of the above
Explanation:
term is used to describe the phase change of a solid to a liquid is Melting.
Question 55. What is the term used to describe the phase change as a liquid becomes a solid?
(b)Condensation
(c)Freezing
(d)None of the above
Explanation:
term used to describe the phase change as a liquid becomes a solid is Freezing.
Question 56. Which has the least energetic molecules?
(b)Liquids
(c)Gases
(d)Plasmas
Explanation:
Solids has the least energetic molecules
Question 57. In which phase of matter would you expect compound (alcohol exists) at room temperature?
(b)Liquid
(c)Gas
(d)Plasma
Explanation:
In Liquid phase of matter would you expect compound (alcohol exists) at room temperature?
Question 58. Which of these choices will not change the state of matter?
(b)Crushing a crystal
(c)Pressure
(d)Heat
Explanation: Crushing a crystal will not change the state of matter.
Question 59. If you leave water in a glass and some molecules turn into a gas, it is called:
(b)Evaporation
(c)Extinction
(d)sublimation
Explanation:
If you leave water in a glass and some molecules turn into a gas, it is called Evaporation.
Question 60. As of the 1990s, scientists have proved the existence of how many states of matter?
(b)Three
(c)Four
(d)Five
Explanation:
As of the 1990s, scientists have proved the existence of Five states of matter.
Question 61. Out of the following which is the densest state of matter?
(b)Liquids
(c)Gases
(d)Plasmas
Explanation:
Solids are the densest state of matter.
Question 62. Which is incorrect statement:
(b)Of the three state of matter, the one that is most compact is solid state.
(c)In solid state inter-particles space (i.e., empty space) is minimum.
(d)The density of solid is generally more than that of a liquid.
Explanation:
Matter is not continuous in nature.
Question 63. Select the one that when used would be considered as best condition for liquification of a gas:
(b)Decreasing the pressure
(c)Increasing the pressure and decreasing the temperature
(d)Decreasing the pressure and increasing the temperature.
Explanation:
Increasing the pressure and decreasing the temperature will lead to liquidification of gas.
Question 64. Which one is a sublime substance?
(b)Sugar
(c)Iodine
(d)Potassium iodide
Explanation:
Iodine is a sublime substance.
Question 65. The one, in which inter-particle forces are strongest, is:
(b)Hydrogen
(c)Ether
(d)Carbon dioxide
Explanation:
Solids have the strongest inter-molecyular force, amognst the materials sodium choloride is only solid so inter-molecular force between it will be the strongst.
Question 66. The melting point temperature of the solid state of a substance is 40°C. The freezing point temperature of the liquid state of the same substance will be:
(b)40°C
(c)45°C
(d)Can’t predict
Explanation:
If melting point is given it can't be predicted that what will be the freezing point of the subbstance.
Question 67. Density of a substance is defined as
(b) product of mass and volume
(c) ratio of mass and temperature
(d) product of mass and temperature
Explanation:
Density of a substance is defined as ratio of mass and volume.
Question 68. Which of the following is not matter
(b) Moon rock
(c) Electron
(d) Humidity
Explanation:
Humididty is not a matter.
Question 69. Which is more effective in cooling?
(b) Water at 273 K
(c) Water at 373K
(d) Ice at 373K
Explanation:
Ice at 273K(0°C) is more effective in cooling.
Question 70. 0 ° C temperature is equal to
(b) 273 K
(c) -273 K
(d) 300 K
Explanation:
0°C = 273K
Question 71. The process involving the change of state from solid to gas is called
(b) boiling
(c) fusion
(d) sublimation
Explanation:
The process involving the change of state from solid to gas is called sublimation.
Question 72.What is the term used to describe the phase change of a liquid to a gas?
(b)Condensation
(c)Melting
(d)None of the above
Explanation:
term used to describe the phase change of a liquid to a gas is Boiling
Question 74.What term is used to describe the phase change of a solid to a liquid?
(b)Melting
(c)Boiling
(d)None of the above
Explanation:
term is used to describe the phase change of a solid to a liquid is Melting.
Question 75.What s the term used to describe the phase change as a liquid becomes a solid?
(b)Condensation
(c)Freezing
(d)None of the above
Explanation:
term used to describe the phase change as a liquid becomes a solid is Freezing.
Question 76. The evaporation of a liquid can best be carried out in a:
(b) China dish
(c) Test tube
(d) Beaker
Explanation:
As china disk has broad base and the rate of evaporation will be carried out best in it.
Question 77. Which one of the following sets of phenomena would increase on raising the temperature?
(b) Evaporation, compression of gases, solubility
(c) Evaporation, diffusion, expansion of gases
(d) Evaporation, solubility, diffusion, compression of gases
Explanation:
Evaporation, diffusion, expansion of gases will take place on raising the temperature.
Question 78. Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her to identify the correct set of conditions.
(b) High temperature, low pressure
(c) Low temperature, high pressure
(d) High temperature, high pressure
Explanation:
Gases can be compressed under low temperature and high pressure. Under these conditions the particles of gases come closer and liquefy.
Question 79. The property to flow is unique to fluids. Which one of the following statements is correct?
(b) Gases and solids behave like fluids.
(c) Gases and liquids behave like fluids
(d) Only liquids are fluids.
Explanation:
Gases and liquids flow due to less intermolecular force in the molecules. Gases and liquids take the shape of the container in which they are put.
Question 80. During summer, water kept in an earthen pot becomes cool because of the phenomenon of
(b) transpiration
(c) osmosis
(d) evaporation
Explanation:
Earthen pot has small pores through which water keeps evaporating and evaporation causes cooling.
Question 81. A few substances are arranged in the increasing order of ‘forces of attraction’ between their particles. Which one of the following represents a correct arrangement?
(b) Air, sugar, oil
(c) Oxygen, water, sugar
(d) Salt, juice, air
Explanation:
Forces of attraction between the particles increase in the order of gases < liquids < solids hence, the correct arrangement is oxygen, water, sugar.
Question 82. On converting 25°C, 38°C and 66°C to Kelvin scale, the correct sequence of temperature will be
(b) 298 K, 300 K and 338 K
(c) 273 K, 278 K and 543 K
(d) 298 K, 310 K and 338 K
Explanation:
K =25 °C + 273
Hence 25°C = 273 + 25 = 298 K
38°C = 273 + 38 = 311 K
66°C = 273 + 66 = 339 K
Question 83. Choose the correct statement of the following.
(b) Conversion of vapours into solid without passing through the liquid state is called sublimation.
(c) Conversion of vapours into solid without passing through the liquid state is called freezing.
(d) Conversion of solid into liquid is called sublimation.
Explanation:
Conversion of vapours into solid without passing through the liquid state is called sublimation.
Question 84. The boiling points of diethyl ether, acetone and n-butyl alcohol are 35°C, 56°C and 118°C respectively. Which one of the following correctly represents their boiling points in Kelvin scale?
(b) 308 K, 329 K, 392 K
(c) 308 K, 329 K, 391 K
(d) 329 K, 392 K, 308 K
Explanation:
35°C = 273 + 35 = 308 K
56°C = 273 + 56 = 329 K
118°C = 273 + 118 = 391 K
Question 85. Which condition out of the following will increase the evaporation of water?
(b) Decrease in temperature of water
(c) Less exposed surface area of water
(d) Adding common salt to water
Explanation:
Rate of evaporation increases with increase in temperature of water.
Question 86. ln which of the following conditions, the distance between the molecules of hydrogen gas would increase?
(i) Increasing pressure on hydrogen contained in a closed container
(ii) Some hydrogen gas leaking out of the container
(iii) Increasing the volume of the container of hydrogen gas.
(iv) Adding more hydrogen gas to the container without increasing the volume of the container.
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii)and(iv)
Explanation:
(ii) If some hydrogen gas is leaked from the container the remaining gas will occupy the whole space and the distance between the molecules will increase.
(iii) If the volume of the container is increased, same number of molecules will occupy that space. Hence, the distance between the molecules will increase.
Question 87. Consider the following statements and choose the correct one(s):
(b) The forces of attraction between the particles are the strongest in solids, less strong in liquids, and negligible in gases.
(c) The movement of particles is the minimum in solids, more in liquids and maximum in gases.
(d) All the above.
Explanation:
Here, all the statements are correct. Hence, your answer will be option (D).
Question 88. In a quiz competition, you are asked a question where you have to choose the statement which is/ are incorrect?
(b) Plasma can also be made on the earth by passing electricity through gases at very low pressure taken in a glass tube.
(c) Plasma is a fifth state of matter.
(d) None of the above.
Explanation:
Plasma is a fourth state of matter and plasma is a mixture of free electrons and ions. Plasma occurs naturally in the stars including the sun.
Question 89. When heat is constantly supplied by a burner to boiling water, then the temperature of water during vaporization:
(b) Rises rapidly until steam is produced
(c) First rises and then becomes constant
(d) Does not rise at all
Explanation:
Temperature of the water during vaporisation does not change at all because the heat is used in overcoming particle-particle attraction forces, which in turn keeps the temperature constant.
Question 90. Gunja is completed her science chapter where she wrote some statements. She wants to know whether the statements are correct or not? Gunja wants to take help from you:
(b) The force of attraction is maximum in the particles of solid matter and minimum in the particles of gases matter.
(c) A material which can flow easily and requires a vessel to keep it called fluid
(d) All the above
Explanation:
Here, all the statements are correct. Hence, your answer will be option (D).
Question 91. Choose the correct statement of the following:
(b) Conversion of vapours into solid without passing through the liquid state is called sublimation.
(c) Conversion of vapours into solid without passing through the liquid state is called freezing.
(d) Conversion of solid into liquid is called sublimation.
Explanation:
Conversion of solid into vapours on heating or vapours into solid on cooling without undergoing in liquid state is called sublimation. The conversion of liquid into gas or vapour is called vaporization. The conversion of liquid into solid is called freezing. The conversion of solid into liquid is called melting.
Question 92. The evaporation of water increases under the following conditions:
(b) Increase in surface area, decrease in temperature
(c) Increase in surface area, rise in temperature
(d) Increase in temperature, increase in surface area, addition of common salt
Explanation:
When surface area increases and temperature rises, evaporation of water increases because the area which is exposed to the outer atmosphere is more and increasing the temperature leads to increase in the kinetic energy, due to which rate of evaporation increases.
Question 93. Priya is writing some statements, choose the correct statement and help him:
(b) A desert cooler cools better on a hot and dry day.
(c) A fan increases the rate of evaporation of sweat or moisture from our skin and make us feel cool and comfortable.
(d) All the above.
Explanation:
Here, all the statements are correct. Hence, your answer will be option (D).
Question 94. In a quiz competition, you are asked a question where you have to choose the statement which is/ are correct?
(b) Solid carbon dioxide is stored under less-high pressure.
(c) The conversion of solid carbon dioxide into carbon dioxide gas is a change of state which is caused by the increase in pressure and decrease atmospheric temperature.
(d) Whatever be the temperature at which evaporation take place, the latent heat of vaporization need not be supplied whenever a liquid change into vapour or gas.
Explanation:
Ammonia gas can be liquefied by applying high pressure and lowering the temperature. In option (B): Solid carbon dioxide is stored under high pressure. In option (C): The conversion of solid carbon dioxide into carbon dioxide gas is a change of state which is caused by the decrease in pressure and increase atmospheric temperature. In option (D): Whatever be the temperature at which evaporation take place, the latent heat of vaporization must be supplied whenever a liquid change into vapour or gas.
Question 95. Which of the following statement is incorrect?
(b) The particles of matter attract one another
(c) The particles of some of the matter are moving constantly
(d) The particles of all the matter have spaces between them
Explanation:
The statement that the particles of some forms of matter move constantly is incorrect because the particles of matter of all three states– solid, liquid and gas –are moving constantly. Although the particles of solids are fixed at their positions, they vibrate constantly.
Question 96. Pankush appeared in class test but he confused to know the correct statement. Would you help him to know that?
(b) All the water on the earth does not get evaporated due to the high value of the latent heat of vaporization of water.
(c) During hot summer days, water is usually kept in an earthen pot to keep it cool.
(d) All the above
Explanation:
Here, all the statements are correct. Hence, your answer will be option (D).
Question 97. Which one of the following statements is not true?
(b) The molecules in a liquid are arranged in a regular pattern
(c) The molecules in a gas exert negligibly small forces on each other, except during collisions
(d) The molecules of a gas occupy all the space available
Explanation:
The above answer is not true because in liquids the molecules are not arranged in regular pattern. In liquids the molecules are loosely arranged.
Question 98. In which of the following conditions, the distance between the molecules of hydrogen gas would increase?
(b) Increasing pressure on hydrogen contained in a closed container and Adding more hydrogen gas to the container without increasing the volume of the container.
(c) Some hydrogen gas leaking out of the container and Increasing the volume of the container of hydrogen gas
(d) Some hydrogen gas leaking out of the container and Adding more hydrogen gas to the container without increasing the volume of the container.
Explanation:
Hydrogen gas leaking from the container leaves some vacant space inside the container. So, hydrogen gas molecules inside the container occupy all the space available and the distance between the molecules of hydrogen gas will be increased. On increasing the volume of the container of hydrogen gas, more space will be available inside the container and hydrogen gas molecule will occupy all the space available and hence distance between the molecules will be increased. On increasing pressure, hydrogen molecules will come closer and the distance between them will be decreased. More hydrogen gas molecules are available in less volume, so the distance between them will be decreased.
Question 99. Pooja is writing some statements but she confused to know whether the statements are correct or not? If you know the answer to this question, then tell her:
(b) The rate of evaporation increases on increasing the temperature of the liquid.
(c) The rate of evaporation decreases on increasing the surface area of the liquid.
(d) When the humidity of air is low then the rate of evaporation is high and water evaporates more easily.
Explanation:
The rate of evaporation increases on increasing the surface area of the liquid.
Question 100. What is the physical state of water 1000°C
(b) Solid
(c) Liquid
(d) Plasma
Explanation:
At 1000°C water will in steam (Gaseous) state.
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