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question_answer1) A sample of water under study was found to boil at 102°C, at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment.
question_answer2) Why are liquids more compressible than solids?
question_answer3) Why a gas cylinder cannot be half-filled?
question_answer4) Why water is a liquid at room temperature?
question_answer5) Give full forms of LPG.
question_answer6) Why is an iron rod solid at room temperature?
question_answer7) Which characteristic of a gas is used in supplying oxygen cylinders to hospitals?
question_answer8) At what temperature, do solid ice and liquid water co-exist together?
question_answer9) Mention two ways to liquefy atmospheric gases.
question_answer10) How do three states of matter arise?
question_answer11) Why should wet clothes be spread while drying?
question_answer12) Why do liquids take up the shape of the container in which they are kept?
question_answer13) Name SI unit of measuring temperature. The boiling point of water is 100°C under normal atmospheric pressure. Convert this temperature to SI units.
question_answer14) Name three states of matter. Which state of matter is rigid and why?
question_answer15) What is the name of the phenomenon of changing a liquid into its vapours at a temperature below its boiling point?
question_answer16) How does the smell of the cooked food reach our nostrils even without our entering the kitchen?
question_answer17) List any two properties of particles of matter?
question_answer18) Convert 370 K into Celsius scale.
question_answer19) What is the full form of CNG? Mention its one property which makes it so important.
question_answer20) What is plasma?
question_answer21) Why does the level of water not change when sugar is dissolved in water?
question_answer22) Rubber band changes its shape. Is it solid?
question_answer23) What is meant by volatile liquid? Give some examples. Sol. The liquids which are easily vaporisable i.e., can easily be converted into vapours are called volatile liquids. For example, acetone, ethanol etc.
question_answer24) Why do liquids show the phenomenon of diffusion to more extent than solids?
question_answer25) Why do liquids flow?
question_answer26) What is meant by latent heat of vaporisation?
question_answer27) A sponge can be compressed. Is it solid or not?
question_answer28) Why do liquids have mostly lower density than solids?
question_answer29) What would be the effect of temperature on the rate of diffusion of liquids?
question_answer30) Why is boiling called a bulk phenomenon?
question_answer31) Why do gases exert more pressure on the walls of the container than the solids?
question_answer32) Name the process by which a drop of spreads in a beaker of water?
question_answer33) What happens to the boiling point of a liquid when atmospheric pressure decreases?
question_answer34) What happens to the melting point of ice when pressure is increased?
question_answer35) What happens to the melting point of solids with the increase in pressure?
question_answer36) What is the latent heat of fusion of ice?
question_answer37) 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 remember the correct set of conditions.
question_answer38) Which conditions will increase the evaporation of water?
question_answer39) Benzene is a liquid. At 80° C liquid benzene is in equilibrium with its vapours. It is found that particles of benzene vapours are more energetic than particles of liquid benzene. Explain the observation.
question_answer40) Name the two gases which are supplied in compressed form in homes and hospitals.
question_answer41) (i) Conversion of solid to vapours is called sublimation. Name the term used to denote the conversion of vapours to solid. (ii) Conversion of solid state to liquid state is called fusion, what is meant by latent heat of fusion?
question_answer42) Osmosis is a special kind of diffusion. Comment.
question_answer43) Water as ice has a cooling effect, whereas water as steam may cause severe burns. Explain these observations.
question_answer44) Carbon dioxideis a gas. Justify the given statement by two reasons.
question_answer45) Ramesh took two beakers A and B containing hot water and cold water respectively. In each beaker, he dropped a crystal of copper sulphate. He kept the beakers undisturbed. After sometime what did he observe and why?
question_answer46) With the help of an activity show that the rate of evaporation increases with increase in surface area.
question_answer47) Explain, which one will cause more severe burns-boiling water at 100°C or steam at 100°C?
question_answer48) How will you change water from gaseous state to liquid state? Suggest a simple activity.
question_answer49) Sodium salt and sugar have similar appearance. Why are these classified as different substances?
question_answer50) Give one similarity and one dissimilarity between a liquid and a gas.
question_answer51) Divide the following substances into two groups (i)With high intermolecular forces (ii)With low intermolecular forces Ice, sulphur, vapour, nitrogen, sugar, copper, air, salt, plastic.
question_answer52) It is not proper to regard the gaseous state of ammonia as vapours. Explain.
question_answer53) Give the conditions in which the distance between the molecules of hydrogen gas would increase.
question_answer54) The table below shows the melting and boiling points of four pure substances. Which substance is a liquid at room temperature and would rapidly evaporates if left exposed to the air? Substance Melting Point/ Boiling Point/ A -100 -35 B -7 58 C -6 225 D 44 280
question_answer55) Out of two gases carbon dioxide and methane which gas would diffuse rapidly?
question_answer56) Give two ways in which melting and boiling points can be useful.
question_answer57) Name the state of matter in which (i) Layers of particles can slip and slide over each other. (ii) Particles just move around randomly, because of very weak force of attraction .
question_answer58) Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.
question_answer59) (i) List three characteristics of particles of matter. Describe one example for each characteristic to illustrate it. (ii) Name the characteristics which are responsible for spreading of smell of scent in a room and (b) water taking the shape of the vessel in which it is poured.
question_answer60) The temperature-time graph given below shows the heating curve for pure wax. From the graph answer the following. (i) What is the physical state of the substance at the points A,B,C, and D? (ii) What is the melting point of the substance? (iii) What is its boiling point? (iv) Which portions of the graph indicates that change of state is taking place? (v) Name the terms used for heat absorbed during change of states involved in the above processes.
question_answer61) (i) What is matter? Write two properties of solids and two properties of liquids. (ii) Give reasons for the following. (a) Ice at 0°C appears colder in the mouth than water at 0°C. (b) Doctors advise to put the strips of wet cloth on the forehead of a person having high temperature.
question_answer62) Differentiate between three states of matter on the basis of the following properties. (i) intermolecular forces (ii) arrangement of molecules
question_answer63) (i) What temperature in Kelvin scale is equal to 50°C? (ii) Describe an activity to show that rate of evaporation increases with surface area. (iii) State two differences between evaporation and boiling.
question_answer64) Fill in the Blanks (i) Evaporation of a liquid at room temperature leads to a ......... effect. (ii) At room temperature, the forces of attraction between the particles of solid substances are ......... than those which exist in the gaseous state. (iii) The arrangement of particles is less ordered in the ......... state. However there is no order in the ......... state. (iv) ............ is the change of gaseous state directly to solid state without going through the ............ state. (v) The phenomenon of change of a liquid into the gaseous state at any temperature below its boiling point is called .........
question_answer65) Benzoic acid is used as a food preservative. The graph below shows the heating curve for benzoic acid. Study the graph and answer the following questions (i) At what time does benzoic acid begin to (a) melt? (b) boil? (ii) What is the melting point of benzoic acid? (iii) What happens to -the temperature while benzoic acid melts? (iv) What is the physical state of benzoic acid during the time interval of 35-45 min?
question_answer66) The following set up kept in a room on a hot summer day shows melting of ice. Rahul observes the changes in temperature at different intervals as follows I. For the first time interval to seconds, the temperature first gradually dropped from 3 0°C to 0°C. II. For the next time interval to seconds, the temperature remained constant until all the ice melted. III. In the next time interval from to seconds, the temperature then increased gradually from 0°C to 100 °C. Draw the graph to show the above mentioned changes. Now answer the following (i) Name the property by virtue of which the temperature remained constant in observation (II). (ii) What should be subsequent reading of temperature on further heating after seconds of Rahul's observation?
question_answer67) Describe the continuous motion of particles of matter with the help of an activity.
question_answer68) The fragrance produced due to burning of incense stick is due to movement of gaseous vapours produced rapidly in all directions. To demonstrate motion of particles of solid matter (a) Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water. (b) Do not stir the solution and allow the crystals to settle at the bottom, (c) The colour of the solid is seen spreading slowly. (d) This is because the solid particles diffuse in the water. (5)
question_answer69) Which of the following are matter? Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume. [NCERT]
question_answer70) What happens when an inflated air balloon is pricked with a pin? Name the property of the gaseous state exhibited by this observation.
question_answer71) Why do solid substances not diffuse?
question_answer72) Give reason for the following observation: The smell of hot sizzling food reaches you several metres away, but to get the smell of cold food you have to go close. [NCERT]
question_answer73) Name the process which occurs when a drop of dettol is added to water.
question_answer74) The mass per unit volume of a substance is called density (density = mass/volume). The following in order of increasing density?air, exhaust from chimneys, honey, water, chalk, cotton and iron. [NCERT]
question_answer75) In which of the following the particles have highest forces of attraction? Water, NaCI (solid), ice or, wax.
question_answer76) Which of the following diffuses faster? Water vapour, wax or, ethyl alcohol.
question_answer77) What is dry ice? Write its chemical formula.
question_answer78) How does perspiration help to maintain the body temperature in summer?
question_answer79) In what ways are materials different from each other?
question_answer80) Is there any similarity in materials?
question_answer81) Can materials exist in all the three states?
question_answer82) When 50 g of sugar is dissolved in 100 mL of water, there is no increase in volume. What characteristic of matter is illustrated by this observation?
question_answer83) Arrange the following substances in increasing order of forces of attraction between the particles - water, sugar, oxygen. [NCERT]
question_answer84) What is the physical state of water at: (a) 25°C (&) 0°C (c) 1 [NCERT]
question_answer85) Why do we see water droplets on the outer surface of a glass containing ice cold water?
question_answer86) Define density and give its SI unit.
question_answer87) Analyse the temperature versus time graph of water, given below. Which region contains all liquids?
question_answer88) Why do the gases exert more pressure on the walls of the container than solids?
question_answer89) For any substance, why does the temperature remain constant during the change of state? [NCERT]
question_answer90) Suggest a method to liquefy atmospheric gases. [NCERT]
question_answer91) Why does a desert cooler cool better on a hot dry day? [NCERT]
question_answer92) You are given the following substances: Ethyl alcohol, glycerol, diethyl ether and water. Arrange these compounds in increasing order of their rate of evaporation.
question_answer93) Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Why? [NCERT]
question_answer94) Give two reasons to justify the following observations: (a) Water at room temperature is a liquid. (b) An iron almirah is solid at room temperature. [NCERT]
question_answer95) Design an experiment to show that ammonium chloride undergoes sublimation.
question_answer96) Why is ice at 273 K more effective in cooling than water at the same temperature? [NCERT]
question_answer97) Name A, B, C, D, E and F in the following diagram showing change in its states, [NCERT]
question_answer98) When a crystal of potassium permanganate is placed in a beaker containing water, its purple colour spreads throughout the water. What do you conclude from this observation about the nature of potassium permanganate and water?
question_answer99) Why does the temperature remain constant during the melting of ice even though heat is supplied continuously?
question_answer100) Explain how the following factors affect the rate of evaporation of a liquid; (i) Temperature of the liquid. (ii) Area of the exposed surface. (iii) Moisture in the surrounding air. (iv) Increase in wind speed.
question_answer101) Why steam at 100°C is better for heating purposes than water at 100°C?
question_answer102) You want to wear your favourite shirt to a party, but the problem is that it is still wet after a wash. What steps would you take to dry it faster?
question_answer103) What type of clothes should we wear in summer? [NCERT]
question_answer104) Convert the following temperatures to the Celsius scale: (a) 293 K (b) 470 K [NCERT]
question_answer105) Convert the following temperatures to the Kelvin scale: (a) 25°C (b) 373°C [NCERT]
question_answer106) Why do the doctors advise to put strips of wet cloth on the forehead of a person having high fever?
question_answer107) A diver is able to cut through water in a swimming pool. Explain. [NCERT]
question_answer108) Write in brief an activity to show the particulate nature of matter. What are the characteristics of the particles of matter? [NCERT]
question_answer109) How does evaporation differ from boiling?
question_answer110) How does the water kept in an earthen pot (matke) become cool during summer? [NCERT]
question_answer111) Explain what happens to the molecular motion and energy of 1 kg of water at 273 K when it is changed into ice at same temperature. How is the late heat of fusion related to the energy exchange that takes place during the change of state?
question_answer112) What do you understand by the term 'latent heat effusion'? How much the latent heat of fusion of ice?
question_answer113) Why do we feel comfortable under a fan when we are perspiring?
question_answer114) A glass tumbler containing hot water is kept in the freezer compartment of refrigerator (temperature <0°C). If you could measure the temperature the content of the tumbler, which of the following graphs would correctly represent the change in its temperature as a function of time? [NCERT Exemplar]
question_answer115) Look at the following figures and suggest in which of the glass containers, i.e., A, B, C or D, the rate of evaporation will be the highest? Explain. [NCERT Exemplar]
question_answer116) Why do solids have a regular geometrical shape?
question_answer117) Why are gases compressible but not liquids?
question_answer118) Why do wet clothes dry quickly in the sun than in the shade?
question_answer119) Why do trees acquire more leaves during summer?
question_answer120) Can a rubber band change its shape on stretching? Is it a solid?
question_answer121) Give two ways in which melting points and boiling points can be useful.
question_answer122) Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered Then the the temperature of the steam was higher than that of the water boiling in the Comment. [NCERT Exemplar]
question_answer123) Why does the temperature of a substance remain constant during it melting point or boiling point? [NCERT Exemplar]
question_answer124) Suggest an activity to show that the rate of diffusion of liquids decrease with increase in density of the liquid.
question_answer125) Give reasons for the following observations: (a)A gas completely fills the vessel in which it is kept. (b) A gas exerts pressure on the walls of the container. (c) Naphthalene balls disappear with time without leaving any 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. [NCERT] (e) Our palm feel cold when we put some acetone or petrol or perfume at it. [NCERT]
question_answer126) (a) Tabulate the differences in the characteristics of the three states of matter. (b) Comment on the following: Rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density. [NCERT]
question_answer127) Discuss the various factors which affect the rate of evaporation. Latent heat of evaporation of two liquids A and B is 100J/kg and 150J/kg respectively Which one can produce more cooling effect and why?
question_answer128) Comment on the following statements: (a) Evaporation causes cooling. (b) Rate of evaporation of an aqueous solution decreases with increase in humidity. (c) Sponge though compressible is a solid, (d) Ice is solid at 0°C, while water is liquid at room temperature. (e) Sugar crystals dissolve faster in hot water than cold water. [NCERT Exemplar]
question_answer129) dissolve them faster than cold water. Describe the continuous motion of particles of matter with the help of an activity.
question_answer130) Describe an activity to determine the boiling point and melting point of ice.
question_answer131) (a) Name the changes in the terms of process P, Q, R and S. (b) Which of the changes are exothermic and endothermic?
question_answer132) You are given the following substances with their melting and boiling points. Substance Melting point Boiling point (°C) X -219 -183 Y 119 445 Z -15 78 Identify the physical states of X, Y and Z at room temperature (30°C).
question_answer133) The diagram below shows burning of an oil lamp. Draw the arrangement of particles of position 'X' and 'Y' when the lamp is burning.
question_answer134) A sample of water under study was found to boil at 102°C at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment. [NCERT Exemplar]
question_answer135) Water as ice has a cooling effect, whereas water as steam may cause severe burns. Explain these observations. [NCERT Exempla]
question_answer136) From the graph given below (i) Which region contains only solid? (ii) Which region contains all liquids? (iii) Which region shows latent heat of vaporisation?
question_answer137) (i) Dry ice is compressed under high pressure. What happens to it when the pressure is released? (ii) Define (a) Melting point (b) Fusion
question_answer138) Classify the following into osmosis/ diffusion. (i) Swelling up of a raisin on keeping in water. (ii) Spreading of virus on sneezing. (iii) Earthworm dying on coming in contact with common salt. (iv) Shrinking of grapes kept in thick sugar syrup. (v) Preserving pickles in salt. (vi) Spreading of smell of cake being baked throughout the house. (vii) Aquatic animals using oxygen dissolved in water during respiration.
question_answer139) Tarun got an invitation to attend a party On coming to his place, he found that both his shirt and pent were wet. What step he would take to dry them quickly?
question_answer140) (i) Why does the temperature of a substance remain constant during its melting or boiling? (ii) A glass tumbler containing hot water is kept in the freezer compartment of a refrigerator (temperature < 0°C). If you could measure the temperature of the content of the tumbler, which of the following graphs would correctly represent the change in its temperature as a function of time.
question_answer141) It is a hot summer day. Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you think would be more comfortable and why?
question_answer142) Look at figure and suggest in which of the vessels A,B,C or D the rate of evaporation will be the highest? Explain.
question_answer143) (i) What determine the state of a substance? (ii) Convert 30°C into Kelvin. (iii) Water droplets are observed on the outer surface of a glass tumbler containing ice cold water. Give reason.
question_answer144) (i) Draw a well labelled diagram showing sublimation of camphor. (ii) Convert : 340 K to degree celsius.
question_answer145) (i) Arrange the following substances in increasing order of force of attraction between the particles. (a) water (b) hydrogen (c) sand (ii) Why does the temperature remain constant at the melting point? (iii) Which property of gases makes it possible to fill large volume of gases in small cylinders?
question_answer146) (i) Water has higher boiling point than alcohol. Give reason. (ii) Find the temperature in Kelvin, at which water can be changed into solid state and vapours.
question_answer147) One day, when Heena was playing with her mother's cosmetics, she felt cold, when a liquid bottle break and some liquid fall on her hand. She got worried. She wash suddenly her hand and ask her mother why she felt cold. Her mother gave her scientific explanation which satisfied her. Read the above passage and answer the following questions. (i) Can you guess what was that liquid? (ii) Why Heena felt cool when liquid fall on her hand? (iii) What values are shown by Heena's mother?
question_answer148) How do you differentiate between solids, liquids and gases on the basis of their melting and boiling points.
question_answer149) While heating ice in a beaker with a thermometer suspended in it, a student recorded the following observations Time 0 1 2 3 4 5 6 7 8 10 15 20 25 30 35 (in min) Temp -3 -1 0 0 5 8 12 15 19 22 30 50 73 100 100 (in °C) Based on the above observations, answer the following questions (i) State the change (s) observed between 2 min to 3 min and name the process involved. (ii) Between 30 min to 35 min, the temperature remains constant. State the reason for this. Name the heat involved in the process and define it.
question_answer150) An inflated balloon goes down because gas molecules can diffuse through the rubber Four balloons are filled with different gases at the same temperature and pressure. Which balloon would go down most quickly?
question_answer151) The cover plate is removed from the gas jars shown in the diagram. After several days, the colour of the gas is the same in both jars. Why does this happen? Explain.
question_answer152) Meera had some guests visiting one Sunday afternoon. While serving them tea from the kettle, a gush of steam suddenly burns her fingers and she feels intense pain. Her mother asks her to keep her fingers under running tap water. After sometime the pain subsides. Answer the following questions based on the above information. (i) What could be the possible reason for the intense pain felt by Meera? (ii) Why does her mother ask her to keep her fingers under tap water? (iii) What values are promoted by Meera's mother?
question_answer153) Madhav feels irritated and upset when heat becomes unbearable during summers especially after rainy season. He wanted to know the reason for this. So he asked his father about the reason behind this phenomenon. His father explained the fact properly. Madhav thanked his father for such explanations. Read the above passage and answer the following questions. (i) How did father of Madhav would have explain the fact? (ii) What are the values shown by Madhav?
question_answer154) Alka's mother bought a new refrigerator which was frost free. Alka was unaware of the frost free technology of refrigerator. She wanted to know about this. So, she asked to her mother about this. (i)What are the values shown by Alka? (ii) How did her mother explain such thing.
question_answer155) Sohan's grandmother used to keep water in an earthen pot. In summer season this earthen pot did not keep water cool. Sohan suggested to his grandmother to change the pot into new one. As such pot was old and its pores were closed by dusty particles that's why pot did not keep water cool. Read the above passage and answer the following questions. (i) How does the water kept in an earther pot cool? (ii) What are the values displayed by Sohan?
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