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IMPORTANT CHEMISTRY QUESTIONS FOR BOARD EXAMINATION  CBSE 2009
Q. 1. H2O is a liquid while H2S is a gas.
Q. 2. HF is a weak acid than HI although F is more electronegative than I.
Q. 3. Nitrogen does not form NCl5 but P forms PCl5.
Q. 4. Give example of a compound in which OS of Chlorine is +7.
Q. 5. Draw the shape of
         i.            XeOF4
        ii.            XeO3.
Q. 6. Which compound led to the discovery of noble gas compounds?
Q. 7. Why noble gases forms compounds only with halogens?
Q. 8. Arrange: MF, MCl, MBr, MI in increasing order of ionic character.
Q. 9. Arrange: NH3, PH3, AsH3, SbH3 in increasing order of Bond strength.
Q. 10. Arrange: HClO, HClO2, HClO3, HClO4 in increasing order of acidic strength.
Q. 11. H3PO3 is diprotic.
Q. 12. OF2 should be called oxygen difluoride and not fluorine oxygen.
Q. 13. PbX2 is more stable than PbX4.
Q. 14. SnCl2 is a solid while SnCl2 is a liquid at room temp.
Q. 15. Noble gases exhibit low reactivity.
Q. 16. Arrange F2, Cl2, Br2, I2 in increasing order of Bond Energy.
Q. 17. Nitrogen exists as N2 gas while Phosphorous exists as P4.
Q. 18. Oxygen is a gas while Sulphur is a solid at room temp.
Or
Oxygen exists as O2 while S exists as S8.
Q. 19. Arrange the halides of group no.17 in increasing order of acidic strength, boiling point, thermal stability, reducing strength, bond dissociation energy.
Q. 20. X2 is a greenish yellow gas with an offensive smell used in water purifications. It partially dissolves in water to give a solution which turns blue litmus red. When X2 is passed through NaBr solution Br2 is obtained.
Identify X2, name the group to which it belongs, write general electronic configuration, what are the products obtained when X2 reacts with H2O. Write eq. also.
Q. 21. Draw the structure of i) orthophosphoric acid ii) Sulphuric Acid
Q. 22. What is Caro?s acid?
Q. 23. Explain why halogens except F show oxidation state of +5, +3, +1 etc (3marks)
Q. 24. What are interhalogen compounds? What are their various types? Give examples of interhalogen compounds. Why are interhalogen compounds more reactive than corresponding halogens? (5)
Q. 25. Why halogens are coloured?
Q. 26. What led to the discovery of noble gases? (3)
Q. 27. How is SO2 an air pollutant?
Q. 28. Halogens have the smallest size in the group. Why?
Q. 29. Noble gases have higher atomic size than expected.
Q. 30. Fluorine has higher EA than chlorine> Explain
 
2 Marks questions
Q. 1. Why water from the soil rises to the top of the trees?
Q. 2. Which substance is added to water in car radiators to act as antifreeze?
Q. 3. What is the expected value of Van?t Hoff Factor for K4[Fe(CN)6]?
Q. 4. How is depression in FP related to molecular mass?
Q. 5. Give relation between normality and molarity of i) 1 M H2SO4 ii) 1M Ca(OH)2.
Q. 6. BP of a solution is always________________ than that of pure solvent.
Q. 7. 2 gm each of solute A and B (molar mass A<B) are dissolved separately in 50 gm of solvent. Which will show greater elevation in BP?
Q. 8. Why is CaCl2 used to clear snow on roads?
Q. 9. The boiling points of ethyl alcohol and methyl alcohol are 78.3ºC and 64.5ºC. Which of them has a higher vapour pressure?
Q. 10. What is an azeotrope?
Q. 11. Define Osmotic Pressure. Arrange the following in increasing order of OP:
1.       34.2 g/L of sucrose (MM = 342)
2.       60 g/L Urea (MM = 60)
3.       90 g/L glucose (MM = 180) iv) 58.5 gm/L of NaCl (MM = 58.5) (Hint g/L means WB/V)
Q. 12. Define i) Normality ii) Mole Fraction.
Q. 13. Define Roult?s Law.
Q. 14. Define Colligative Property. Show that relative lowering in vapour pressure is equal to mole fraction of solute.
Q. 15. Explain why addition of solute lowers freezing point of sol. Draw the graph also.
3 Marks questions
Q. 16. A commercially available sample of sulphuric acid contains 25% H2SO4 by weight (density = 1.10 g/ml) Calculate
         i.            Molarity
        ii.            Normaility
      iii.            Molality.
Q. 17. A solution containing 0.5 gm of KCl dissolved in 100 gm of water freezes at -0.240C. Calculate the degree of dissociation of salt. Kf for water = 1.86.
Q. 18. Osmotic Pressure of Blood is 8.21 atm at 370C. How much glucose should be used per litre for an intravenous injection that is isotonic with blood?
5 Marks questions
Q. 19. Define Van?t Hoff Factor. Why do some solutes show abnormal molar masses? Give the value of Van?t Hoff Factor for i) Association ii) Dissociation iii) Non-Electrolytes. How do colligative properties get modified with help of Van?t Hoff Factor. Give equation only.
Q. 20. Define and give characteristics of ideal and non-ideal solutions. With the help of graph and examples explain types of non-ideal solutions.
 
Q. 1. Why do amines act as nucleophile?
Q. 2. Name the follwong according to IUPAC system:
CH3COCH2COCH3.
Q. 3. What are azeotropes?
Q. 4. State condition resulting in reverse osmosis.
Q. 5. Write the IUPAC names of BHC OR DDT.
Q. 6. Convert: i) Propene to propan-2-ol (ii) Anisole to phenol
Q. 7. How would you account for following:
         i.            Sulpher hexafluoride is less reactive than sulphur tetrafluoride.
        ii.            Of the noble gases only Xe forms chemical compounds.
Q. 8. Arrange: CH3OH, (CH3)2CHOH, (CH)3-C-OH in Increasing order of
         i.            Acidic strength
        ii.            Reactivity towards HCl.
Q. 9. Arrange RF, RCl, RBr, RI in increasing order of
         i.            BP
        ii.            Polarity
Q. 10. Arrange the following:
         i.            MF, MCl, MBr, MI (Increasing order of ionic character)
        ii.            NH3, PH3, AsH3, SbH3 (Increasing order of basic strength)
Q. 11. Write short notes on i) diazotization ii) Coupling.
Q. 12. Account for the following:
1.       Methyl amine has lower BP than methanol.
2.       Methyl amine is a stronger base than ammonia.
Q. 13. Write chemical equation to illustrate:
a.       Rosenmund Reduction
b.       Cannizaro Reaction
c.        Fischer Esterification.
Q. 14. Account for any two of the following:
a.       Amines are basic substances while amides are neutral.
b.       Alkyl halides have higher BP than hydrocarbons with almost same Molecular mass.
c.        Aromatic amines are weaker bases than aliphatic amines.
Q. 15. Why aniline is more reactive than benzene? Why for halogenation of aniline, it is first treated with acetic anhydride?
Or
Arrange primary, secondary, tertiary amines in increasing order of basic strength.
Q. 16. Arrange:
a.       o-methyl aniline, m-methyl aniline, p-methyl aniline, aniline and m-nitro aniline in increasing order of basic strength.
b.       o-hydroxy benzoic acid, p-hydroxy benzoic acid, m-hydroxy benzoic acid and benzoic acid (increasing order of acidic strength)
Q. 17. Explain:
         i.            Gabriel pthalamide synthesis
        ii.            Aldol Condensation
      iii.            Arrange: Acetic acid, 1-chloroacetic acid, 1,1-dichloroaceic acid, 1,1,1-trichloroacetic acid in increasing order of acidic strength.
Q. 18. What is Van?t Hoff Factor? Why do some solutes show abnormal molecular masses? What is the value of Van?t Hoff Factor for
a.       Association
b.       Dissociation
c.        Non-electrolytes.
Q. 19. Account for following:
a.       Oxygen is a gas while sulphur is a solid at room temp.
b.       Nitrogen does not form NCl5 but P forms PCl5.
c.        Halogens have the smallest size in the group.
Q. 20. Distinguish between any three:
a.       Propanone and Benzaldehyde
b.       Benzaldehyde and Acetaldehyde
c.        ethanol and phenol
d.       Chlorobenzene and chloro cyclohexane
Q. 21. Convert:
a.       Ethanamine to methanamine
b.       Methanamine to ethanamide
c.        Phenol to phenolphthalein
Q. 22. Why haloalkanes undergo nucleophilic substitution rxn while haloarenes undergo electrophilic substitution rxn?
Q. 23. A 0.1539 molal aq solution of cane sugar (MM = 342gm) has a FP of 271 K while FP of pure water is 273.15K. What will be FP of a aq solution containing 5 gm of glucose (MM = 180gm) per 100 gm of solution.
Q. 24. Write short notes on
a.       Carbylamine or Riemer Teimann Rxn.
b.       Preparation of carboxylic acid from Grignard Reagent.
Q. 25. Assign Reasons for following:
1.       Acidic Strength of acids is HF<HCl<HBr<HI
2.       SnCl4 is a liquid while SnCl2 is a solid.
3.       SnCl4is less stable than SnCl2.
4.       H3PO2 behaves as a monoprotic acid.
5.       Noble gases exhibit low chemical reactivity.
Or
a.       What are interhalogen compounds? What are their types? Give examples. Why are interhalogen compounds more recative than corresponding halogens? (3)
b.       Arrange: i) HClO, HClO2, HClO3, HClO4 (Increasing Acidic Strength)
c.        Hydrides of group 17 (Thermal stability and Reducing Character)
Q. 26. Convert:
a.       Chlorobenzene to phenol
b.       Phenol to 2-acetoxy benzoic acid
c.        Benzene to m-nitro benzene
d.       Toluene to Benzyl Chloride
e.       2-propanol to 1-bromopropane.
Q. 27.
a.       Define Roult?s Law for a solution containing non volatile solute.(1)
b.       Explain why a mixture of ethyl alcohol and cyclohexane shows +ve deviation from Roult?s Law. (2)
c.        Arrange:1m NaCl, 1m CaCl2, 1m glucose (increasing order of elevation in BP)
d.       Give one use of reverse osmosis.
 
Q. 1. Draw the resonating structures of
a.       NO
b.       NO2
c.        N2O
d.       N2O3
e.       N2O4
f.         N2O5.
g.       O3.
Also draw the structures of each clearly depicting the bond parameters.
Q. 2. Draw the resonance structures of SO2.
Q. 3. Draw the structures of
a.       NH3
b.       HNO3
c.        White phosphorus
d.       Red phosphorus
e.       PCl3
f.         PCl5
g.       Phosphoric acid
h.       Phosphorus acid
i.         Hypo phosphorus acid
j.         Pyro phosphoric acid
k.        cyclic tri meta phosphoric acid
l.         Poly meta phosphoric acid.
m.     S8
n.       S6
o.       Sulphuric acid
p.       sulphurus acid
q.       Peroxo di sulphuric acid
r.         Pyro sulphuric acid (oleum)
s.       HOCl
t.         HClO2
u.       HClO3
v.        HClO4
w.      BrF3
x.        IF5
y.        IF7
z.        IF4- aa) SF4 bb) SF6 cc) XeOF4 dd) BrO3- ee) XeF2 ff) XeF4 gg) XeF6 hh) XeOF4 ii) XeO3
Q. 4. Give the formula and structure of noble gas species which is iso structural with
a.       ICl4-
b.       IBr2-
c.        IF6-
d.       BrO3-
Q. 5. Why does nitrogen shows anomalous behavior? Give examples to show the anomalous behavior of nitrogen.
Q. 6. Why does oxygen shows anomalous behavior? Give examples to show the anomalous behavior of oxygen.
Q. 7. Why does fluorine shows anomalous behavior? Give examples to show the anomalous behavior of fluorine.
Q. 8. Describe the method of preparation of
a.       NH3 by Haber procssssess
b.       HNO3 by Ostwald process
c.        H2SO4 by contact process.
Give three uses of each.
Q. 9. Explain brown ring test for nitrate with suitable equations.
Q. 10. What is disproportionation reaction? Give equation of the reactions involved in the disproportionation of
a.       HNO2
b.       Se2Cl2
c.        H3PO2
Q. 11. How is ozone estimated quantitatively?
Q. 12. Give two uses each of
a.       N2
b.       PH3
c.        O2
d.       Ozone
e.       SO2
f.         Cl2
g.       ClO2
h.       BrO3
i.         I2O5
j.         Cl2 k) HCl
k.        ClF3
l.         He
m.     Ne
n.       Ar
o.       Kr
p.       Xe
Q. 13. How is NH3(aq) used in salt analysis to determine the presence of
a.       Fe3+
b.       Zn2+
c.        Ag+
in salt analysis. Write the equations of the reactions involved.
Q. 14. How is the presence of SO2 detected?
Q. 15. What is aqua regia? How does it dissolve noble metals like Au and Pt? Write the equations of the reactions involved.
Q. 16. Give differences between white phosphorus and red phosphorus.
Q. 17. How is
a.       N2
b.       O2
c.        Cl2 prepared in the laboratory? Write the equations of the reactions involved.
Q. 18. How is
a.       N2
b.       O2
c.        Cl2 manufactured in the industry? Write the equations of the reactions involved in the manufacture of Cl2.
Q. 19. How is ammonia prepared in laboratory? Write the equation of the reaction involved.
Q. 20. How is HNO3 prepared in laboratory? Write the equation of the reaction involved.
Q. 21. How is phosphine prepared from
a.       Calcium phosphide
b.       White phosphorus.
Write the equations of the reactions involved.
Q. 22. How is PCl5 prepared from
a.       Cl2
b.       SO2Cl2?
Write the equations of the reactions involved
Q. 23. How is PCl3 prepared from
1.       Cl2
2.       SOCl2?
Write the equations of the reactions involved
Q. 24. How is HCl prepared from NaCl? Write the equations of the reactions involved
Q. 25. Write the chemical formula of
a.       Chile saltpetre
b.       Indian saltpetre
c.        Fluorapatite
d.       Gypsum salt
e.       Epsom salt
f.         Baryte
g.       Galena
h.       Zinc blende
i.         Copper pyrite
j.         Florospar
k.        cryolite
l.         Fluoroapatite
m.     carnalite.
n.       Tear gas
o.       mustard gas
p.       Phosgene
Q. 26. With what neutral molecule ClO- is iso electronic? Is that molecule a lewis base?
Q. 27. Compare the chemistry of Sulphur.What is the transition temperature of Sulphur.
Q. 28. How is phosphine purified? Write the equations of the reactions involved.
 


Q. 1. There is a considerable increase in covalent radius from N to P but from As to Bi only a small change is observed.
Q. 2. Ionisation enthalpy of group 15 elements is much higher than that of group 14 elements.
Q. 3. Ionic radius of Sb and Bi are very less when compared to the ionic radius of N,P and As.
Q. .4. Metallic character of group 15 elements decreases on going down the group.
Q. .5. Tendency to show ? 3 oxidation states in group 15 decreases on going down the group.
Q. .6. Nitrogen can?t form penta halides.
Q. 7. Nitrogen exhibits bonding while heavier members exhibit bonding.
Q. 8. N2 is a gas while P4 is a solid.
Q. 9. Catenation tendency is weaker in nitrogen.
Q. 10. N2 molecule is chemically inert while white phosphorus is more reactive.
Q. 11. In group 15, +3 oxidation state is more stable than +5 oxidation state on going down the group .
Q. 12. R3 P=O is known but R3 N=O is unknown.
Q. 13. Basicity of hydrides NH3> PH3 > AsH3 > SbH3 > BiH3
Q. 14. Stability of hydrides NH3> PH3 > AsH3 > SbH3 > BiH3
Q. 15. Reducing character of hydrides NH3< PH3 < AsH3 < SbH3 <BiH3
Q. 16. The oxides in higher oxidation states of group 15 elements are more acidic than that of lower oxidation state.
Q. 17. Basicity of group 15 oxides increases on going down the group.
Q. 18. PCl5 is more covalent than PCl3.
Q. 19. PCl5 is more covalent than PF5.
Q. 20. All the five bonds in PCl5 are not equivalent.(Or) PCl5 is more reactive than PCl3.
Q. 21. Both PCl3 and PCl5 fumes in air.
Q. 22. PH3 has lower boiling point than NH3.
Q. 23. NH3 acts as a lewis base.
Q. 24. NO2 molecule dimerise to become N2O4.
Q. 25. Aluminium is rendered passive in concentrated HNO3.
Q. 26. Concentrated HNO3 becomes yellow when exposed to light.(Or) concentrated HNO3 is an oxidizing agent.
Q. 27. White phosphorus is more reactive than red phosphorus. Black phosphorus is least reactive.
Q. 28. Bond angle in PH3+ is higher than that of PH3.
Q. 29. HNH bond angle in NH3 is less than the tetra hedral bond angle of 109.50.
Q. 30. Bond angles of HPH,HAsH and HSbH are closer to 900.
Q. 31. H3PO4 is tri protic, H3PO3 is diprotic while H3PO2 is mono protic.
Q. 32. H3PO2 is a good reducing agent.
Q. 33. H3PO2 is a stronger reducing agent than H3PO3.
Q. 34. NO is an odd electron molecule but does not dimerise to give N2O2.
Q. 35. Sulphur has very high boiling and melting point when compared to oxygen.
Q. 36. In group 16 tendencies to show -2 oxidation state decreases on going down the group.
Q. 37. In group 16 +4 oxidation state become more stable than +6 oxidation state on going down the group.
Q. 38. Oxygen can show a maximum covalency of 4 and it can not form hexa valent compound.
Q. 39. Acidity of group 16 hydrides H2O <H2 S < H2Se < H2Te.
Q. 40. Reducing character of group 16 hydrides H2O <H2 S < H2Se < H2Te
Q. 41. Boiling point of H2O is higher than that of H2 S.
Q. 42. Sulphur exhibit +6 oxidation state when it combines with fluorine.
Q. 43. SF6 is exceptionally stable or it can not be hydrolysed easily.
Q. 44. SF6 is known while SCl6 is unknown.


Q. 45. SF6 is known while SH6 is unknown.
Q. 46. H2O is a liquid while H2S is a gas.
Q. 47. MnO is basic while Mn2O7 is acidic.
Q. 48. O3 is thermo dynamically unstable than O2 (or) . O3 in higher concentration is explosive.
Q. 49. NO gas depletes ozone layer.
Q. 50. Sulphur in vapour state is paramagnetic.
Q. 51. HCl and HNO3 are prepared by reacting NaCl and NaNO3 respectively with H2SO4 while HBr and HI can?t be prepared by this method.
Q. 52. Cane sugar chars in concentrated sulphuric acid.
Q. 53. Concentrated sulphuric acid is a good oxidizing agent.
Q. 54. Two S-O bonds in SO2 are equivalent.
Q. 55. Ka2 of H2SO4 is << Ka1.
Q. 56. Halogens have maximum negative electron gain enthalpy in each period.
Q. 57. Fluorine has lesser negative value of electron gain enthalpy than chlorine.
Q. 58. All halogens are colored.
Q. 59. F2 has smaller enthalpy of dissociation than Cl2.
Q. 60. Fluorine has lesser negative value of electron gain enthalpy than chlorine but fluorine is a stronger oxidizing agent than chlorine.
Q. 61. Fluorine shows only ? 1 oxidation state. Other halogens can exhibit positive oxidation state.
Q. 62. Halogens show positive oxidation state when they combine with oxygen and fluorine atoms.
Q. 63. Halogens are good oxidizing agent and oxidizing power (reactivity) decreases with the increase in atomic number.
Q. 64. Most of reactions of fluorine are exothermic.
Q. 65. HF is a liquid while other hydrogen halides are gases.
Q. 66. HF has highest boiling point while HCl has lowest boiling point among hydrogen halides.
Q. 67. Acidity of hydrogen halides HF < HCl < HBr < HI
Q. 68. Thermal stability of hydrogen halides HF > HCl > HBr > HI
Q. 69. Thermal stability of group 16 hydrides H6O > H6S > H6Se > H6Te
Q. 70. OF2 is fluoride of oxygen and not oxide of fluorine.
Q. 71. Oxygen and chlorine has similar electro negativity. Oxygen form hydrogen bonding but not chlorine.
Q. 72. .Ionic character of halides MF>MCl>MBr>MI
Q. 73. Electron gain enthalpy of O O- is ? 141 KJ/mole and O O --> O2- is + 702 KJ/mole. Large number of oxides having O2- is known and not O-.
Q. 74. In metal halides, halides in higher oxidation state of the metal is more covalent than the one in lower oxidation state.(PbCl4 is more covalent than PbCl2)
Q. 75. Inter halogen compound is more reactive than the halogens from which it is formed.
Q. 76. Chlorine is a powerful bleaching agent.
Q. 77. HCl reacts with Fe to give FeCl2 and not FeCl3
Q. 78. Fluorine forms only one oxo acid HOF
Q. 79. Acidity of oxo acids HClO4> HClO3> HClO2> HC1O.
Q. 80. Acidity of oxo acids HOCl>HOBr>HOI
Q. 81. Oxidizing power of HClO4> HClO3> HClO2> HClO
Q. 82. Fluorine form fluoride of oxygen while other halogens form oxides of halogen.
Q. 83. Group 18 elements are chemically unreactive.
Q. 84. Group 18 elements have very high ionization enthalpy and it decreases on going down the group.
Q. 85. Group 18 elements have positive value of electron gain enthalpy.
Q. 86. Group 18 elements have lower value of boiling and melting point and it increases on going down the group.
Q. 87. Group 18 elements have larger atomic radius.
Q. 88. Bartlett synthesized XePtF6 from his knowledge of earlier known compound O2PtF6.
Q. 89. Xenon forms noble gas compounds.
Q. 90. Xenon forms compounds only with oxygen and fluorine.
Q. 91. Helium is used in diving apparatus.
Q. 92. Oxygen has lesser negative value of electron gain enthalpy than Sulphur.

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