1. Fill in the blanks (a) In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called ————. (b) A group of atoms carrying a fixed charge on them is called ————. (c) The formula unit mass of Ca3 (PO4)2 is -------------------- (d) Formula of sodium carbonate is ———— and that of ammonium sulphate is ————. 2. Compute the difference in masses of 103 moles each of magnesium atoms and magnesium ions. (Mass of an electron = 9.1×10 –31 kg) 3. Which has more number of atoms? 100g of N2 or 100 g of NH3 4. Compute the number of ions present in 5.85 g of sodium chloride. 5. A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present in one gram of this sample of gold? 6. What are ionic and molecular compounds? Give examples. 7. Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is 9.1×10 –28 ) g). Which one is heavier? 8. A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament. 9. A sample of ethane (C2H6) gas has the same mass as 1.5 ×10 20 10. What is the fraction of the mass of water due to neutrons? 11. Does the solubility of a substance change with temperature? Explain with the help of an example. 12. Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24g mol -1 13. Verify by calculating that (a) 5 moles of CO2 and 5 moles of H2O do not have the same mass. (b) 240 g of calcium and 240 g magnesium elements have a mole ratio of 3:5. 14. A sample of vitamic C is known to contain 2.58 ×10 24 oxygen atoms. How many moles of oxygen atoms are present in the sample? 15. The visible universe is estimated to contain 10 22 stars. How many moles of stars are present in the visible universe? 16. Compare the properties of electrons, protons and neutrons. 17. What are the limitations of J.J. Thomson’s model of the atom? 18. What are the limitations of Rutherford’s model of atom? 19. Describe Bohr’s model of atom.
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Transcript
1. Fill in the blanks
(a) In a chemical reaction, the sum of the masses of the reactants and products remains
unchanged. This is called ————.
(b) A group of atoms carrying a fixed charge on them is called ————.
(c) The formula unit mass of Ca3 (PO4)2 is --------------------
(d) Formula of sodium carbonate is ———— and that of ammonium sulphate is ————.
2. Compute the difference in masses of 103 moles each of magnesium atoms and magnesium
ions.
(Mass of an electron = 9.1×10–31 kg)
3. Which has more number of atoms? 100g of N2 or 100 g of NH3
4. Compute the number of ions present in 5.85 g of sodium chloride.
5. A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present
in one gram of this sample of gold?
6. What are ionic and molecular compounds? Give examples.
7. Compute the difference in masses of one mole each of aluminium atoms and one mole of its
ions. (Mass of an electron is 9.1×10–28 )
g). Which one is heavier?
8. A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of
silver. Compute the ratio of the number of atoms of gold and silver in the ornament.
9. A sample of ethane (C2H6) gas has the same mass as 1.5 ×1020
10. What is the fraction of the mass of water due to neutrons?
11. Does the solubility of a substance change with temperature? Explain with the help of an
example.
12. Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g.
Molar atomic mass of magnesium is 24g mol-1
13. Verify by calculating that
(a) 5 moles of CO2 and 5 moles of H2O do not have the same mass.
(b) 240 g of calcium and 240 g magnesium elements have a mole ratio of 3:5.
14. A sample of vitamic C is known to contain 2.58 ×1024 oxygen atoms. How many moles of
oxygen atoms are present in the sample?
15. The visible universe is estimated to contain 1022 stars. How many moles of stars are present
in the visible universe?
16. Compare the properties of electrons, protons and neutrons.
17. What are the limitations of J.J. Thomson’s model of the atom?
18. What are the limitations of Rutherford’s model of atom?
19. Describe Bohr’s model of atom.
20. Compare all the proposed models of an atom given in this chapter.
21.Summarize the rules for writing of distribution of electrons in various shells for the first
eighteen elements.
22. Define valency by taking examples of silicon and oxygen
23. Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars.
Give any two uses of isotopes.
24. Na+ has completely filled K and L shells. Explain.
25. If bromine atom is available in the form of, say, two isotopes 7935Br (49.7%) and 81
35Br (50.3%), calculate the average atomic mass of bromine atom.
GUESS PAPER SUMMATIVE ASSESSMENT –I (2011) SCIENCE- Class – IX (Chemistry)GUESS PAPER SUMMATIVE ASSESSMENT –I (2012) Class – IX (Chemistry
Section A
1.What is dry ice ? What happens when the pressure under which it is stored is decreased to
1 atmosphere ?
2.Why is glass or chinaware packed with straw ?
3.Name the processes by which CO2 and H2O move into and out of the cell ?
4.List in tabular form any two differences between homogeneous and heterogeneous mixtures.
5. (a) Define evaporation. (b) 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.
6.(i) Name the process or the separation technique you would follow to separate : (a) Dyes in black ink (b) Butter from cream (c) Ammonium chloride and common salt (d) Iron filings and sand (ii) State the principle used in separation by centrifugation.
7. Based on the following characteristics distinguish in tabular form the behavior of true solution, suspension and colloidal solution. (a) appearance (b) visibility (c) filterability (d) Tyndall effect (e) particle size OR
(a) What is distillation ? List the two conditions essential for using this as a method of separation of components of a mixture. (b) Draw a labelled diagram of the apparatus used to separate a mixture of two miscible liquids.
8..Compare in tabular form , the properties of Solids, Liquids and Gases with respect to : (i) Shape (ii) Volume (iii) Compressibility (iv) Diffusion (v) Fluidity or Rigidity
OR ,
Account for the following : (a) For any physical state of a substance, the temperature remains constant during its change of state. (b) Water kept in an earthen pot becomes cool in summer. (c) We are able to sip hot tea from a saucer rather than from a cup.
Section B
09.If common salt is added to the unsaturated solution of water and common salt it
will
(a) become a colloid (b) become a suspension (c) start showing Tyndall effect (d) remain a true solution
10.A student was asked to mix the white of an egg with water and stir well. The student observed that
(a) a transparent solution is formed. (b) a translucent mixture is formed.
(c) egg white settles down at the bottom. (d) egg white floats on the surface.
11.The reaction of iron and sulphur to form iron sulphide takes place at :
(a) at high temperature (b) in the presence of a catalyst
(c) at moderate temperature (d) in the presence of an acid
12.Which of the following compounds when dissolved in water gives coloured solution ?
13.For determining the accurate melting point of ice we should prefer
(a) ice made from distilled water (b) ice made from tap water
(c) crushed dry ice mixed with salt (d) a mixture of ice and salt
14.Mohan used a thermometer having 20 divisions between 30degC mark and 40degC mark. While determining boiling point of water using this thermometer he observed that the level of mercury becomes constant just 3 division below the 100o C mark. Mohan should record in his note book
(a) Least count=0.5degC, B.P.=97degC (b) L.C.=0.5degC, B.P.=98.5degC
15.Ramu was asked to separate a mixture of common salt and ammonium chloride. Sublimation is used to separate ammonium chloride because :
(a) ammonium chloride sublimes
(b) ammonium chloride changes directly from solid to gaseous state on heating
(c) mixture contain a sublimable volatile component and a non Sublimable impurity (salt)
(d) all the above
16.Which is the correct colour sequence of iron filings, sulphur and iron sulphide ?
(a) Greyish black, yellow, black (b) Black, yellow, brown
(c) Brown, yellow, black (d) Black , yellow, greyish black
17.The colour of magnesium after rubbing with sand paper is
(a) Silvery white (b) Grey (c) Black (d) Brown
18.Common salt and sand can be separated by :
(a) Filtration (b) Crystallisation (c) Sedimentation and Decantation
(d) First dissolving in water, then by filtration and followed by crystallisation.
19.A student put five raisins each in two beakers A and B. Beaker A contained 20 mL ofdistilled water and beaker B has 20 mL of saturated sugar solution. After some time the student would observe that :
(a) raisins in beaker A were more swollen than those in beaker B.
(b) raisins in beaker B were more swollen than those in beaker A.
(c) raisins in both beakers A and B were equally swollen.
(d) raisins in beaker A did not swell up at all.
20.In the preparation of temporary mount of onion peel which of the following is not used :
(a) water (b) glycerine (c) safranin (d) alcohol
21.Arun, Deepa, Uma and Priya were asked to select a plant material which would not give blue black colour with iodine solution. Who did not select the right material ?
(c) Uma selected ground nut seeds. (d) Priya selected potato.
22.Deepak washed a few grains of tur dal in water. The water became yellow. He then added a few drops of HCl to the same test tube, the water turned pink in colour. From the above test Deepak concluded that tur dal contains. (a) proteins (b) starch (c) turmeric (d) metanil yellow HCl
23.A student recorded the mass of dry raisins as 2.5g and the mass of raisins after soaking in water as 4 g . While performing the above experiment. The percentage of water absorbed by raisin is :
(a) 20% (b) 30% (c) 60% (d) 40%
24.The mixture of sand and water when filtered gives.
(a) pale brown solution (b) brown solution
(c) transparent solution (d) grey solution
25. When a mixture of sulphur powder and iron filings is heated.
(a) iron filings starts melting (b) sulphur sublimates leaving iron filling behind
(c) ferrous sulphide is formed. (d) sulphur melts
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IX Chemistry Sample paper 2012
One mark each:
1. Define atomic mass unit?
2. Define Mole?
3. An atom has electronic configuration of 2, 8, 7
(1)What is the atomic number of the element?
(2)Which of the following elements have same number of valence electrons
N(7), F(9), P(15), Ar(18)
4. Why are He, Ne and Ar are Inert?
5. Why are all electrons called fundamental particles of all atoms?
6. Calculate the value of moles in 17g of H2O2.[(H =1u), O =16u]
7. What is meant by Avogadro ‘s constant?
8. State Law of conservation of mass.
9. Calculate the number of molecules in 4g of methane (C=12u, H =1u)
10. What are isotopes? Give examples.
2 marks each:
11. What is the electronic configuration of Na+,if atomic No, of Na atom is 11.What is the atomic
No. and atomic mass of Na+ .
12.Which of the two would be chemically more reactive element ‘X’ of atomic No.18 or element
‘Z’ of atomic No. 16 and why?
13.What is the difference between sodium atom and sodium ion?
14.How many molecules are present in
(a) 9g of water (b) 17g of NH3 .
(H = 1u, O = 16u, N =14u)
15.Calcium and Oxygen are combined in the rates of 5:4 by mass to form calcium oxide. What
mass of oxygen gas would be required to react with 2.5g of calcium?
16.How many atoms of carbon and hydrogen are present in 3 moles of ethane
( C2 H6 ).
17.The atomic number of Aluminum is 13 and that of Chlorine is 17.How many electrons ,
protons and neutrons are present in Al3 and Cl- ions.
18.What you meant by valence electrons?
(1) Write the electronic configuration of elements potassium (19) and N (7)
(2)Write the No.of valance electrons in each of these elements?
19.An element has three valence electrons in the 3rd shell. Name the element and give its atomic
No. and state is it a metal or non-metal?
20.Calculate the mass of 6.022 x 10 23 N2 molecules. (N = 14u)
3 mark each:
21. Write the chemical formula for the following:
(1) Ammonium Carbonate.
(2)Barium Sulphate.
(3) Sodium Sulphide.
(4)Aluminium Hydroxide.
(5)Calcium Flouride.
(6)Potassium Nitrate.
22. Calculate the molecular mass of the following:
(i)(NH4)2SO4 (ii)Al2(SO4)3 (iii) Ca(HCO3)2
[ N = 14u, H =1u, S = 32u, Al = 27u, O = 16u, C = 12u ]
23.Calculate the No.of Al3+ ions present in 0.056g of Al2O3.
24.What is chemical formula? Give two information conveyed by chemical formula of a
compound.
25.Explain Rutherford’s Alpha Scattering experiment for the discovery of Nucleus. Write his
observations and conclusions.
26.The average atomic mass of a sample of an element X is 16.2u.What are the percentages of
isotopes 16X8and 18X8 in the sample.
27.(1) An ion M3+ has 10 electrons and 14 neutrons. What is the atomic number and mass
number of M.
(2) Write the electronic configuration of the following ions.
(1) Mg2+ (2) O2- (3)S2- (4) Na+ (5) N3-
28. (1) Which has more No.of atoms, 100g of Sodium or 100g of Iron
(Na =23u, Fe = 56u).
(2) Which has more No.of molecules, 4g of CH4 and 8g of H2O
[ H = 1u, O = 16u, C = 12u ]
29. (1) For the symbol, H,Dand T Calculate three subatomic particles found in each of them?
30.If Chlorine atom is available in the form of say two isotopes 17Cl35 (75%)and 17CL37(25%),
Calculate the average atomic mass of chlorine atom.
5 Mark Questions:
31. (1) Explain Bohr model of an atom?
(2)Draw the Bohr model of the following atom
(1) Sodium (11Na23)
(2) Oxygen (8O16)
(3) Calcium (20Ca40)
32.(1) Calculate the molecular mass of the following :
(1) CH3-OH (2) CuSO4.5H2O (3) Ca(HCO3)2
(2)Calculate the No.of particles in each of the following:
(1) 46g of Na atoms (Na = 23u)
(2) 8g of O2 molecules
(3)0.1 mole of carbon atoms
(4)100g of CH4
33. (1)What are the postulates of Dalton’s Atomic theory of matter?
(2)Define the following terms:
(i) Atomicity (ii) Valency (iii) Relative atomic mass (iv) Molecular mass
GUESS PAPER SUMMATIVE ASSESSMENT –I (2011) SCIENCE- Class – IX (Chemistry)GUESS PAPER SUMMATIVE ASSESSMENT –I (2012) Class – IX (Chemistry
Section A
1.What is dry ice ? What happens when the pressure under which it is stored is decreased to
1 atmosphere ?
2.Why is glass or chinaware packed with straw ?
3.Name the processes by which CO2 and H2O move into and out of the cell ?
4.List in tabular form any two differences between homogeneous and heterogeneous mixtures.
5. (a) Define evaporation. (b) 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.
6.(i) Name the process or the separation technique you would follow to separate : (a) Dyes in black ink (b) Butter from cream (c) Ammonium chloride and common salt (d) Iron filings and sand (ii) State the principle used in separation by centrifugation.
7. Based on the following characteristics distinguish in tabular form the behavior of true solution, suspension and colloidal solution. (a) appearance (b) visibility (c) filterability (d) Tyndall effect (e) particle size OR
(a) What is distillation ? List the two conditions essential for using this as a method of separation of components of a mixture. (b) Draw a labelled diagram of the apparatus used to separate a mixture of two miscible liquids.
8..Compare in tabular form , the properties of Solids, Liquids and Gases with respect to : (i) Shape (ii) Volume (iii) Compressibility (iv) Diffusion (v) Fluidity or Rigidity
OR ,
Account for the following : (a) For any physical state of a substance, the temperature remains constant during its change of state. (b) Water kept in an earthen pot becomes cool in summer. (c) We are able to sip hot tea from a saucer rather than from a cup.
Section B
09.If common salt is added to the unsaturated solution of water and common salt it will
(a) become a colloid (b) become a suspension (c) start showing Tyndall effect (d) remain a true solution
10.A student was asked to mix the white of an egg with water and stir well. The student observed that
(a) a transparent solution is formed. (b) a translucent mixture is formed.
(c) egg white settles down at the bottom. (d) egg white floats on the surface.
11.The reaction of iron and sulphur to form iron sulphide takes place at :
(a) at high temperature (b) in the presence of a catalyst
(c) at moderate temperature (d) in the presence of an acid
12.Which of the following compounds when dissolved in water gives coloured solution ?
13.For determining the accurate melting point of ice we should prefer
(a) ice made from distilled water (b) ice made from tap water
(c) crushed dry ice mixed with salt (d) a mixture of ice and salt
14.Mohan used a thermometer having 20 divisions between 30degC mark and 40degC mark. While determining boiling point of water using this thermometer he observed that the level of mercury becomes constant just 3 division below the 100o C mark. Mohan should record in his note book
(a) Least count=0.5degC, B.P.=97degC (b) L.C.=0.5degC, B.P.=98.5degC
15.Ramu was asked to separate a mixture of common salt and ammonium chloride. Sublimation is used to separate ammonium chloride because :
(a) ammonium chloride sublimes
(b) ammonium chloride changes directly from solid to gaseous state on heating
(c) mixture contain a sublimable volatile component and a non Sublimable impurity (salt)
(d) all the above
16.Which is the correct colour sequence of iron filings, sulphur and iron sulphide ?
(a) Greyish black, yellow, black (b) Black, yellow, brown
(c) Brown, yellow, black (d) Black , yellow, greyish black
17.The colour of magnesium after rubbing with sand paper is
(a) Silvery white (b) Grey (c) Black (d) Brown
18.Common salt and sand can be separated by :
(a) Filtration (b) Crystallisation (c) Sedimentation and Decantation
(d) First dissolving in water, then by filtration and followed by crystallisation.
19.A student put five raisins each in two beakers A and B. Beaker A contained 20 mL ofdistilled water and beaker B has 20 mL of saturated sugar solution. After some time the student would observe that :
(a) raisins in beaker A were more swollen than those in beaker B.
(b) raisins in beaker B were more swollen than those in beaker A.
(c) raisins in both beakers A and B were equally swollen.
(d) raisins in beaker A did not swell up at all.
20.In the preparation of temporary mount of onion peel which of the following is not used :
(a) water (b) glycerine (c) safranin (d) alcohol
21.Arun, Deepa, Uma and Priya were asked to select a plant material which would not give blue black colour with iodine solution. Who did not select the right material ?
(c) Uma selected ground nut seeds. (d) Priya selected potato.
22.Deepak washed a few grains of tur dal in water. The water became yellow. He then added a few drops of HCl to the same test tube, the water turned pink in colour. From the above test Deepak concluded that tur dal contains. (a) proteins (b) starch (c) turmeric (d) metanil yellow HCl
23.A student recorded the mass of dry raisins as 2.5g and the mass of raisins after
soaking in water as 4 g . While performing the above experiment. The percentage of water absorbed by raisin is :
(a) 20% (b) 30% (c) 60% (d) 40%
24.The mixture of sand and water when filtered gives.
(a) pale brown solution (b) brown solution
(c) transparent solution (d) grey solution
25. When a mixture of sulphur powder and iron filings is heated.
(a) iron filings starts melting (b) sulphur sublimates leaving iron filling behind
(c) ferrous sulphide is formed. (d) sulphur meltsSaturday, August 11, 2012
9th Chemistry : MCQ Is Matter around us pure Practical based Guess Questions
9th Chemistry : MULTIPLE CHOICE QUESTION ON PRACTICLE SKILLS
EXPERIMENT NO –2
1. Which one of the following is an example of heterogeneous mixture
a. NaCl + water b. kerosene + water
c. sugar + water d. alum + water
2. Which one of the following is a mixture of two elements
a. iron fillings + sulphur powder b. sugar + common salt
c. water +milk d. air
3. Which one is not the property of a mixture
a. heterogeneous b. variable composition
c . constant composition d. none of these
4.Correct method of separating iron fillings from sulphur powder
a. heating in china dish b. heating in boiling tube
c. heating in water d. moving magnet
5. In the formation of which one a large quantity of heat is involved
a. compound b. colloid
c. true solution d. each one
6. When a magnet is moved through of iron fillings and sulphur powder , then
a. iron fillings will cling to magnet b. black mass is produced
c. sulphur will cling to magnet d. none of these
7.When a mixture of iron fillings is heated with sulphur powder
a. nothing happens b. black mass is formed
c. yellow mass is formed d. white mass is formed
8. which one is a mixture
a. salad of fruits b. air
c. sea water d. all of the above
9. Name the process of conversion of solid to vapor
a. evaporation b. fusion
c. distillation d. sublimation
10.Which one of the following is a pure substance
a.milk b.cold drink
c .carbon d oxide d. brass
11.What is observed when iron fillings and sulphur powder is heated in a china dish
a. sulphur melts b. iron melts
c. mixture evaporates d.. yellow mass is formed
12. Mixture is always –
a. homogenous b. heterogeneous
c. homogenous or heterogeneous d. none of these
13. Compound is always –
a. homogenous b. heterogeneous
c. homogenous or heterogeneous d. none of these
14..Which of the following is a compound
a. blood b. air
c. soil d. water
15.On heating iron and sulphur in a china dish
a. mixture is formed b. compound is formed
c. both are formed d. no change
CBSE TEST PAPER Chapter : Matter in Our Surroundings
CBSE TEST PAPER Chapter : Matter in Our Surroundings
1. State whether True or False.(i) Water has no definite shape; therefore, it is not matter.(ii) Gases expand to fill the space available.
2. A substance has a definite volume, but no definite shape. State whether this substance is solid, liquid or gas.
3. Which physical state of matter is the densest?
4.What are the different factors affecting evaporation?
5.Give two reasons as to why a block of ice is considered as matter.
6. Why does matter change state?
7. It is observed that water boils at lower temperature at higher altitudes. Why?
8. If some alcohol is rubbed on the hand, the rubbed portion of the hand feels cool. Why?
9. Name the following.(i) State of matter having the maximum intermolecular space(ii) Force between particles of matter(iii) State of matter with only one free surface
10. A large crystal of potassium permanganate is kept in a glass beaker containing water. This setup is then left undisturbed for an hour. The solution undergoes a change in colour.
(i) What is this change in colour?(ii) Why does such a change take place?
You might also like: Chemistry Guess Questions Banks :Matter in Our Surroundings CBSE SOLVED TEST PAPERS CLASS - IX Science (Is matter around us pure) Class–IX CHEMISTRY Chapter-2:IS MATTER AROUND US PURE CCE Class IX Chapter: Is matter around us pure : Fill In the Blanks MCQ 9th Questions on Practical Skills Experiment No.--1 Chemistry: Is Matter around us Pure
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Chemistry Guess Questions Banks :Matter in Our Surroundings
Chemistry Adda Class IX, Chemistry Guess Questions Banks
Chapter 1: Matter in Our Surroundings
1. What are the different states of matter? Why do matter exist in these different states? [2]
2. Why is ice at 273k is more effective in cooling than water at same temperature? [2]
3. Give reasons. a. Naphthalene balls disappear with time without leaving any residue.
4. b. We can get the smell of perfume sitting several meters away [2]
5. What is the physical state of water at a)30oC b)0oC c)100oC
6. What type of clothes should we wear in summer? [2]
7. How does the water kept in an earthen pot (matka) become cool during summer? [2]
8. Why are we able to sip hot tea or milk faster from a saucer rather than a cup? [2]
9. Why does a desert cooler cool better on a hot dry day? [2]
10. For any substance, why does the temperature remain constant during its phase change?[2]
11. What is sublimation? [2]
12. Give reasons for - [3]The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
13. Give reasons for : How does evaporation cause cooling? [3]
14. Explain giving an activity that the liquids differ in their relative diffusion rates [3]
15. Differentiate between evaporation & boiling. [3]
16. Give two reasons to justify.(a) Water at room temperature is a liquid(b) An iron almirah is a solid at room temperature. [3]
17. Give reasons- [3]
(A) A gas fills completely the vessel in which it is kept.
(B) A gas exerts pressure on the walls of the container.
(C) A wooden table should be called a solid.
18. What are the characteristics of the particles of matter? [3]
19. A diver is able to cut through water in a swimming pool. Which property of matter does this observation prove? [3]
20. What will happen if we put an animal cell or a plant cell into a solution of sugar or salt in water? [3]
21. Define the following terms.
Fusion, latent heat of fusion, boiling point, latent heat of vaporization and sublimation. [3]Thursday, September 20, 2012
GUESS PAPER SUMMATIVE ASSESSMENT –I (2011) SCIENCE- Class – IX (Chemistry)
GUESS PAPER SUMMATIVE ASSESSMENT –I (2012) Class – IX (Chemistry
1.What is dry ice ? What happens when the pressure under which it is stored is decreased to
1 atmosphere ?
2.Why is glass or chinaware packed with straw ?
3.Name the processes by which CO2 and H2O move into and out of the cell ?
4.List in tabular form any two differences between homogeneous and heterogeneous mixtures.
5. (a) Define evaporation. (b) Explain how the following factors affect the rate ofevaporation 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.
6.(i) Name the process or the separation technique you would follow to separate : (a) Dyes in black ink (b) Butter from cream (c) Ammonium chloride and common salt (d) Iron filings and sand (ii) State the principle used in separation by centrifugation.
7. Based on the following characteristics distinguish in tabular form the behavior of true solution, suspension and colloidal solution. (a) appearance (b) visibility (c) filterability (d) Tyndall effect (e) particle size OR
(a) What is distillation ? List the two conditions essential for using this as a method of separation of components of a mixture. (b) Draw a labelled diagram of the apparatus used to separate a mixture of two miscible liquids.
8..Compare in tabular form , the properties of Solids, Liquids and Gases with respect to : (i) Shape (ii) Volume (iii) Compressibility (iv) Diffusion (v) Fluidity or Rigidity
OR ,
Account for the following : (a) For any physical state of a substance, the temperature remains constant during its change of state. (b) Water kept in an earthen pot becomes cool in summer. (c) We are able to sip hot tea from a saucer rather than from a cup.
Section B
09.If common salt is added to the unsaturated solution of water and common salt it will
(a) become a colloid (b) become a suspension (c) start showing Tyndall effect (d) remain a true solution
10.A student was asked to mix the white of an egg with water and stir well. The student observed that
(a) a transparent solution is formed. (b) a translucent mixture is formed.
(c) egg white settles down at the bottom. (d) egg white floats on the surface.
11.The reaction of iron and sulphur to form iron sulphide takes place at :
(a) at high temperature (b) in the presence of a catalyst
(c) at moderate temperature (d) in the presence of an acid
12.Which of the following compounds when dissolved in water gives coloured solution ?
13.For determining the accurate melting point of ice we should prefer
(a) ice made from distilled water (b) ice made from tap water
(c) crushed dry ice mixed with salt (d) a mixture of ice and salt
14.Mohan used a thermometer having 20 divisions between 30degC mark and 40degC mark. While determining boiling point of water using this thermometer he observed that the level of mercury becomes constant just 3 division below the 100o C mark. Mohan should record in his note book
(a) Least count=0.5degC, B.P.=97degC (b) L.C.=0.5degC, B.P.=98.5degC
15.Ramu was asked to separate a mixture of common salt and ammonium chloride. Sublimation is used to separate ammonium chloride because :
(a) ammonium chloride sublimes
(b) ammonium chloride changes directly from solid to gaseous state on heating
(c) mixture contain a sublimable volatile component and a non Sublimable impurity (salt)
(d) all the above
16.Which is the correct colour sequence of iron filings, sulphur and iron sulphide ?
(a) Greyish black, yellow, black (b) Black, yellow, brown
(c) Brown, yellow, black (d) Black , yellow, greyish black
17.The colour of magnesium after rubbing with sand paper is
(a) Silvery white (b) Grey (c) Black (d) Brown
18.Common salt and sand can be separated by :
(a) Filtration (b) Crystallisation (c) Sedimentation and Decantation
(d) First dissolving in water, then by filtration and followed by crystallisation.
19.A student put five raisins each in two beakers A and B. Beaker A contained 20 mL of distilled water and beaker B has 20 mL of saturated sugar solution. After some time the student would observe that :
(a) raisins in beaker A were more swollen than those in beaker B.
(b) raisins in beaker B were more swollen than those in beaker A.
(c) raisins in both beakers A and B were equally swollen.
(d) raisins in beaker A did not swell up at all.
20.In the preparation of temporary mount of onion peel which of the following is not used :
(a) water (b) glycerine (c) safranin (d) alcohol
21.Arun, Deepa, Uma and Priya were asked to select a plant material which would not give blue black colour with iodine solution. Who did not select the right material ?
(c) Uma selected ground nut seeds. (d) Priya selected potato.
22.Deepak washed a few grains of tur dal in water. The water became yellow. He then added a few drops of HCl to the same test tube, the water turned pink in colour. From the above test Deepak concluded that tur dal contains. (a) proteins (b) starch (c) turmeric (d) metanil yellow HCl
23.A student recorded the mass of dry raisins as 2.5g and the mass of raisins after soaking in water as 4 g . While performing the above experiment. The percentage of water absorbed by raisin is :
(a) 20% (b) 30% (c) 60% (d) 40%
24.The mixture of sand and water when filtered gives.
(a) pale brown solution (b) brown solution
(c) transparent solution (d) grey solution
25. When a mixture of sulphur powder and iron filings is heated.
(a) iron filings starts melting (b) sulphur sublimates leaving iron filling behind
(c) ferrous sulphide is formed. (d) sulphur melts
Q.1. What are Canal rays?Q.2. On the basis of Thomson’s model of an atom explain
how the atom is neutral as a whole.
Q.3 Draw a sketch of Bohr’s model of an atom with three shells.
Q.4. Helium atom has atomic mass of 4u and has two protons in the nucleus. How
many neutrons does it have?
Q.5. If the K and L shells of an atom are full, then what would be the number of
electrons in the atom?
Q.6. If the number of electrons in an atom is 8 and the number of protons is also 8,
then;
(i) What would be the atomic number of the atom? (ii) What is the charge on the
atom?
Atomic Structure John Dalton-Rutherford-J.J. Thomson- Atomic Model
Atomic Structure
The word atom originally meant a smallest possible particle of matter, not further
divisible.
Democritus
1. The existence of atoms was proposed as early as in the 5th century BC by the
Greek
philosophers Leucippus and his pupil Democritus, for which they were called
atomists.
2. Democritus, develop the idea of atoms. He asked this question: If you break a
piece of matter in half, and then break it in half again, how many breaks will you
have to make before you can break it no further?
3. Democritus thought that it ended at some point, a smallest possible bit of matter.
He called these basic matter particles, atoms.
4.The word "atom" is derived from the Greek word "atomos", which means
indivisible".
John Dalton
1. Five main points of Dalton's Atomic Theory
• All matter is composed of extremely small particles called atoms.
• All atoms of a given element are identical, having the same size, mass, and
chemical
properties. Atoms of a specific element are different from those of any other
element.
• Atoms cannot be created, divided into smaller particles, or destroyed.
• Different atoms combine in simple whole-number ratios to form compounds.
• In a chemical reaction, atoms are separated, combined, or rearranged.
Weakness
1. Atoms consist of even smaller particles called electrons, protons and neutrons.
2. Atoms can be created and destroyed in the nuclear reactions such as nuclear
fusion and nuclear fission.
Atoms of the same element can have different physical properties, for example,
isotopes of hydrogen.
J.J. Thomson Plum pudding model
1. In physics, the Plum pudding model of the atom was made after the discovery of
the electron and was proposed by the discoverer of the electron, J. J. Thomson.
2. In it, the atom is envisioned as electrons surrounded by a soup of positive charge,
like plums surrounded by pudding.
3. The electrons were positioned uniformly throughout the atom.
4. Instead of a soup, the model is also said to have had a cloud of positive charge.
5. This model can be compared to a British treat called plum pudding, hence the
name. It is alsoknown as the chocolate chip cookie model.
Ernest Rutherford Gold foil experiment
The Gold foil experiment, or Geiger-Marsden experiment was an experiment done
by Hans
Geiger and Ernest Marsden in 1909, under the direction of Ernest Rutherford at the
Physical
Laboratories of the University of Manchester which led to the downfall of the plum
pudding modelof the atom.
1. They measured the deflection of alpha particles directed normally onto a sheet of
very thin gold foil.
2. Under the prevailing plum pudding model, the alpha particles should all have
been deflected by at most of a few degrees.
3. However they observed that a very small percentage of particles were deflected
through angles much larger than 90 degrees.
4. From this Rutherford concluded that the atom contained a very small positive
charge which could repel the alpha particles if they came close enough.
Rutherford Atom
1. Early in 1911 Rutherford published a revised model of the atom, known as the
Rutherford atom.
2. He concluded that
• the atom is mostly empty space,
• most of the atom's mass concentrated in a tiny center, the nucleus and electrons
being held
in orbit around it by electrostatic attraction.
• The nucleus was around 10-15 meters in diameter, in the centre of a 10-10 metre
diameter atom.
• Those alpha particles that had come into close proximity with the nucleus had
been strongly
Model: Solar System Model (Bohr’s Model)
1. Niels Bohr improved on Rutherford's atomic model.
2. Bohr model depicts the atom as a small, positively charged nucleus surrounded
by electrons in orbit - similar in structure to the solar system, but with electrostatic
forces providing attraction, rather than gravity.
3. According to Bohr’s Model
• Electrons in an atom of an element are not randomly distributed around the
atomic nucleus.
• Electrons move around the nucleus in fixed orbits.• Each orbit forms a circle and
has a fixed distance from the nucleus.
James Chadwick’s Model
In 1932, James Chadwick bombarded beryllium (Be) with alpha aprticles. He
allowed the radiation emitted by beryllium to incident on a paraffin wax. It was
found that protons were shot out form the paraffin wax. People began to look for
what was in the "beryllium radiations". 1. Chadwick discovered the presence of
neutrons in the nucleus.
2. He concluded that the nucleus contains another tiny particle known as a neutron
that has nocharge.
3. The neutron mass is almost similar to the proton mass.
4. All nuclei contain protons and neutrons, except for the hydrogen which contains
protons. only
Modern Atomic Model
1. The atomic model in the present day is based on the contributions of the above
scientists.
2. According to the modern atomic model,
(a) The central nucleus consists of protons and neutrons. It containing almost all
the mass of the atom.
(b) the nucleus of an atom is very small compared to the size of the atom
(c) the electrons are orbiting outside the nucleus in the electron shells(d) the
electrons are moving in electron shells at a very high speed and we cannot
determine theposition of the electrons at a particular time
The subatomic particles of an atom
1. Atoms are made up of tiny particles called subatomic particles.
2. An atom contains three types of subatomic particles:a. proton,b. neutron andc.
electron,
3. The proton and neutron form the nucleus at the centre of an atom.
4. The electron moves around the nucleus at a very high speed.
5. The nucleus is positively charged because of the presence of protons, which are
positivelycharged. The neutrons are neutral.
Proton number and nucleon number
Proton Number
1. The proton number (Z) represent the number of protons found in the nucleus of
an atom.
Proton number = the number of protons
2. The proton number is also known as the atomic number.
3. In an atom of neutral charge, the number of electrons also equals the atomic
number.
4. Hence, the proton number of an atom can also represent the number of
electrons.
Nucleon Number
1. The nucleon number (A), also called atomic mass number or mass number, is the
number ofprotons plus the number of neutrons in an atomic nucleus.
Nucleon number = Number of protons + Number of Neutrons
The nucleon number of an atom is about the same as the mass of the atom because
the mass of anelectron is very small and can be ignored.Continued>>>>>>>>>>Read more to excelIX Atomic Structure ( a fundamental particles) Discovery of Electron
9th Atomic Structure (Discovery of a fundamental particle protons)
9th Atoms and Molecules
9th Structure of Atoms
Practice paper and sample paper based On Atomic structure
Saturday, December 3, 2011
9th CBSE Science Chap 3 Atoms and Molecules Test paper
1. Fill in the blanks
(a) In a chemical reaction, the sum of the masses of the reactants and products remains
unchanged. This is called ————.
(b) A group of atoms carrying a fixed charge on them is called ————.
(c) The formula unit mass of Ca3 (PO4)2 is --------------------
(d) Formula of sodium carbonate is ———— and that of ammonium sulphate is ————.
2. Compute the difference in masses of 103 moles each of magnesium atoms and magnesium
ions.
(Mass of an electron = 9.1×10–31 kg)
3. Which has more number of atoms? 100g of N2 or 100 g of NH3
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Wednesday, August 31, 2011
9th CBSE Science Chap 3 Atoms and Molecules Self ...9th CBSE Science Chap 3 Atoms and Molecules Self ...: 1. Fill in the blanks (a) In a chemical reaction,
the sum of the masses of the reactants and products remains unchanged. This is called —...
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9th Atoms and Molecules - Mole Concept and Proble...9th Atoms and Molecules - Mole Concept and Proble...: Mole Concept we can express the quantity
of a substance is expressed in terms of mole. Mole is a fundamental unit in the System Internatio...
Since ammonium ions produce hydroxide ions, NH4+ are considered to be
the basic components.
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Why are commercial samples of bleaching powder not completely soluble in water?Why are commercial samples of bleaching powder not completely soluble in
water?
Because it is essentially chlorinated CaO, which is insoluble. It releases
chlorine on adding to water. Stable bleaching powder has about 37%