Class 11 Chemistry
Final Series Assignment
Assertion Reason Questions Set 2
The questions given below consist of an Assertion and the Reason. Choose:
(a) If both Assertion and Reason are CORRECT and Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are CORRECT, but Reason is NOT THE CORRECT explanation of the Assertion.
(c) If Assertion is CORRECT but Reason is INCORRECT.
(d) If Assertion is INCORRECT but Reason is CORRECT.
(e) If both Assertion and Reason are INCORRECT.
8. Redox Reactions
Q.1. Assertion: 3ClO– → ClO3– + 2Cl– is an example of dissociation reaction.
Reason: ClO– gets oxidised as well as reduced.
Q.2. Assertion: A substance which gets reduced can act as reducing agent.
Reason: An oxidising agent itself gets oxidised.
Q.3. Assertion: Copper sulphate solution is not stored in zinc vessel.
Reason: Zinc forms complex with copper sulphate.
Q.4. Assertion: The Daniell cell becomes dead after sometime.
Reason: Oxidation potential of zinc anode decreases and that of copper cathode increases.
Q.5. Assertion: In iodometric titrations, starch is used as an indicator.
Reason: Starch is a polysaccharide.
Q.6. Assertion: Oxidation state of hydrogen in H2O is +1 and in CaH2 it is –1.
Reason: CaH2 is metal hydride and for hydrides, hydrogen is assigned the oxidation state of –1.
Q.7. Assertion: Oxidation number of C in HCHO is zero.
Reason: Formaldehyde is a covalent compound.
Q.8. Assertion: Oxygen has oxidation state of –2 in both O2 and O3.
Reason: Oxygen is assigned an oxidation state of –2 in almost all its compounds.
Q.9. Assertion: Oxidation number of phosphorus in P4 is zero.
Reason: Phosphorus has oxidation state zero in all its compounds.
Q.10. Assertion: Redox reactions are also called neutralisation reactions.
Reason: The number of electrons gained or lost in the reaction are balanced.
Answers
1. (d) 2. (e) 3. (c) 4. (a) 5. (b) 6. (a)
7. (b) 8. (d) 9. (c) 10. (d)
9. Hydrogen
Q.11. Assertion: Permanent hardness of water is removed by treatment with washing soda.
Reason: Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.
Q.12. Assertion: Some metals like platinum and palladium, can be used as storage media for hydrogen.
Reason: Platinum and palladium can absorb large volumes of hydrogen.
Answers
11. (a) 12. (a)
10. The s-Block Elements
Q.13. Assertion: BeCl2 is covalent whereas MgCl2 and CaCl2 are ionic.
Reason: Beryllium is the first member of the group.
Q.14. Assertion: Beryllium can form BeF42– while aluminium can also form AlF63– ion.
Reason: Beryllium does not have vacant d-orbitals in its outermost shell.
Q.15. Assertion: K, Rh and Cs can also form superoxides.
Reason: Their ionic radii increase in the order Cs+ < Rb+ < K+.
Q.16. Assertion: Cu2Cl2 is more covalent than NaCl.
Reason: Cu+ ion is more polarizing than Na+ ion.
Q.17. Assertion: Be gives characteristic flame colouration.
Reason: Ionization energy of Be is high.
Q.18. Assertion: Beryllium carbonate is kept in the atmosphere of carbon dioxide.
Reason: Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.
Q.19. Assertion: The carbonate of lithium decomposes easily on heating to form lithium oxide and CO2.
Reason: Lithium being very small in size polarises large carbonate ion resulting the formation of more stable Li2O and CO2.
Q.20. Assertion: LiCl is predominantly covalent compound.
Reason: The electronegativity difference between Li and Cl is too small.
Q.21. Assertion: Na2SO4 is soluble in water while BaSO4 is insoluble.
Reason: Lattice energy of barium sulphate exceeds its hydration energy.
Q.22. Assertion: Al(OH)3 is amphoteric in nature.
Reason: Al–O and O–H bonds can be broken with equal lease in Al(OH)3.
Q.23. Assertion: Barium is not required for normal biological function in human.
Reason: Barium does not show variable oxidation state.
Q.24. Assertion: Li resembles Mg.
Reason: Li+ has same size as Mg2+.
Q.25. Assertion: Alkali metals impart colour to the flame.
Reason: Their ionization energies are low.
Q.26. Assertion: Sulphur is estimated as BaSO4 and not as MgSO4.
Reason: The ionic radius of Mg2+ is smaller than that of Ba2+.
Answers
13. (b) 14. (a) 15. (c) 16. (a) 17. (d) 18. (a) 19. (a)
20. (c) 21. (a) 22. (a) 23. (b) 24. (a) 25. (a) 26. (b)
11. The p-Block Elements
Q.27. Assertion: Boric acid behaves as weak monobasic acid.
Reason: It has only one ionizable hydrogen.
Q.28. Assertion: Glass is not an example of silicates.
Reason: All silicates have tetrahedral SiO44– unit.
Q.29. Assertion: Graphite is good conductor of heat and electricity.
Reason: Graphite has π-electrons which are mobile.
Q.30. Assertion: Silicones are water repelling in nature.
Reason: Silicones are organosilicon polymers, which have (–R2SiO–) as repeating unit.
Q.31. Assertion: If aluminium atoms replace a few silicon atoms in three-dimensional network of silicon dioxide, the overall structure acquires a negative charge.
Reason: Aluminium is trivalent while silicon is tetravalent.
Q.32. Assertion: N2 is less reactive than P4.
Reason: Nitrogen has more electron gain enthalpy than phosphorus.
Q.33. Assertion: HNO3 makes iron passive.
Reason: HNO3 forms a protective layer of ferric nitrate on the surface of iron.
Q.34. Assertion: Boron has low electrical conductivity
Reason: At ordinary temperature, boron behaves as metal.
Q.35. Assertion: Diborane forms two three centred electron pair bonds.
Reason: B2H6 does not have sufficient number of electrons to form normal covalent bonds.
Q.36. Assertion: Graphite is soft and a good lubricating agent.
Reason: The successive layers in graphite are held together by weak forces of attraction.
Q.37. Assertion: Diamond is a bad conductor of electricity.
Reason: All C–C bond lengths in diamond are of 154 pm.
Q.38. Assertion: TlCl is more stable than TlCl3.
Reason: +1 oxidation state of heaviest element is more stable than +3.
Q.39. Assertion: Carbon dioxide has linear geometry involving sp hybridisation of C.
Reason: Dry ice is solid CO2.
Q.40. Assertion: Boron does not form BF63– ion while AlF63– is known.
Reason: B does not have d-orbitals in valence shell while Al has d-orbitals in valence shell.
Answers
27. (c) 28. (d) 29. (a) 30. (b) 31. (a) 32. (c) 33. (c)
34. (c) 35. (a) 36. (a) 37. (b) 38. (a) 39. (b) 40. (a)
12. Organic Chemistry – Basic Principles
Q.41. Assertion: Dumas method is more applicable to nitrogen containing compounds than Kjeldahl's method.
Reason: Kjeldahl's method does not give satisfactory results for compounds in which nitrogen is bonded to oxygen.
Q.42. Assertion: Butane and 2-methyl butane are homologues.
Reason: Butane is a straight chain alkane while 2-methyl butane is a branched chain alkane.
Q.43. Assertion: Methylene has a sextet of electrons.
Reason: Methylene behaves as a nucleophile.
Q.44. Assertion: CH3C+=O behaves as electrophile.
Reason: In this species, O has two pairs of electrons.
Q.45. Assertion: All the C–C bond lengths in benzene are equivalent.
Reason: The resonance energy of benzene is about 150.6 kJ mol–1.
Q.46. Assertion: Simple distillation can help in separating a mixture of propan-1-ol (boiling point 97°C) and propanone (boiling point 56°C).
Reason: Liquids with a difference of more than 20°C in their boiling points can be separated by simple distillation.
Q.47. Assertion: All the carbon atoms in H2C=C=CH2 are sp2 hybridised.
Reason: In this molecule all the carbon atoms are attached to each other by double bonds.
Q.48. Assertion: Allyl free radical is more stable than simple free radical.
Reason: The allyl free radical is stabilized by resonance.
Q.49. Assertion: In allene (C3H4) all carbon atoms are sp2 hybridised.
Reason: All the three carbon atoms are joined by double bond.
Q.50. Assertion: Lassaigne's test is not shown by diazonium salts.
Reason: Diazonium salts lose N2 on heating much before than they have a chance to react with fused sodium.
Q.51. Assertion: Mixture of o-nitrophenol and p-nitrophenol can be separated by steam distillation.
Reason: p-nitrophenol is steam volatile while o-nitrophenol is not steam volatile.
Q.52. Assertion: The Lassaigne extract is boiled with dil. HNO3 before testing for halogens.
Reason: The Lassaigne extract is boiled with dil. HNO3 before testing for halogens.
Q.53. Assertion: Ag2S is soluble in HNO3.
Reason: (CH3)3C+ is less stable than (CH3)2CH2+ ion.
Q.54. Assertion: Alkanes having more than three carbon atoms exhibit chain isomerism.
Reason: All carbon atoms in alkanes are sp3 hybridized.
Q.55. Assertion: Sulphur present in an organic compound can be estimated quantitatively by Carius method.
Reason: Sulphur is separated easily from other atoms in the molecule and gets precipitated as light yellow solid.
Q.56. Assertion: Components of a mixture of red and blue inks can be separated by distributing the components between stationary and mobile phases in paper chromatography.
Reason: Coloured components of inks move at different rates because paper selectively retains different components according to difference in their partition between two phases.
Q.57. Assertion: Pent-1-ene and pent-2-ene are position isomers.
Reason: Position isomers differ in the position of functional group or a substituent.
Answers
41. (b) 42. (b) 43. (c) 44. (c) 45. (b) 46. (a) 47. (d)
48. (a) 49. (d) 50. (a) 51. (c) 52. (c) 53. (e) 54. (b)
55. (e) 56. (a) 57. (a)
13. Hydrocarbons
Q.58. Assertion: Nitration of nitrobenzene gives mainly m-dinitro benzene.
Reason: –NO2 group is electron donation group.
Q.59.
Assertion:
is aromatic.
Reason: It contains 4π electrons.
Q.60. Assertion: Buta-1, 3- diene and but- 1- yne can be distinguished with Tollen's reagent.
Reason: But-1-y ne gives ppt. with Tollen's reagent but but-1,3-diene does not.
Q.61. Assertion: Toluene on Friedel Crafts methylation gives o-and p-xylene.
Reason: CH3– group bonded to benzene ring increases electron density at o- and p- position.
Q.62. Assertion: Among isomeric pentanes, 2, 2- dimethylpentane has highest boiling point.
Reason: Branching does not affect the boiling point.
Q.63. Assertion: Nitration of benzene with nitric acid requires the use of conc. sulphuric acid.
Reason: The mixture of concentrated sulphuric acid and concentrated nitric
acid produces the electrophile, 
.
Q.64. Assertion: Addition of Br2 to but-1-ene gives two optical isomers.
Reason: The product contains one asymmetric carbon atom.
Q.65. Assertion: Alkyl benzene is not prepared by Friedel Crafts alkylation of benzene
Reason: Alkyl halides are less reactive than acyl halides.
Q.66. Assertion: Lactic acid shows geometrical isomerism.
Reason: It has C = C bond.
Q.67. Assertion: Trans-but-2-ene on reaction with Br2 gives meso-2, 3-dibromobutane.
Reason: The reaction involves syn-addition of bromine.
Q.68. Assertion: Acetylene is more acidic than ethylene.
Reason: Acetylene has sp character of carbon and, therefore, more s-character.
Q.69. Assertion: Propene reacts with HBr in the presence of peroxides to give 1- bromopropane.
Reason: Alkenes react with HBr in the presence of peroxides according to anti Markovnikov's rule.
Q.70. Assertion: Terminal alkynes on oxidation with Bayer's reagent give a mixture of carboxylic acid and CO2.
Reason: Terminal alkynes show acidic character.
Answers
58. (c) 59. (d) 60. (a) 61 (a) 62. (e) 63. (a) 64. (a)
65. (a) 66. (b) 67. (d) 68. (a) 69. (a) 70. (b)
14. Environmental Chemistry
Q.71. Assertion: Ozone is destroyed by solar radiation in upper stratosphere.
Reason: Depletion of the ozone layer allows excessive UV radiations to reach the surface of earth.
Q.72. Assertion: Excessive use of chlorinated synthetic pesticides causes soil and water pollution.
Reason: These pesticides are non-biodegradable.
Q.73. Assertion: The pH of acid rain is less than 5.6.
Reason: Carbon dioxide present in the atmosphere dissolves in rain water and forms carbonic acid.
Q.74. Assertion: If BOD level of water in a reservoir is less than 5 ppm it is highly polluted.
Reason: High BOD means low activity of bacteria in water.
Q.75. Assertion: Greenhouse effect was observed in houses made of green glass which are used to grow plants.
Reason: Greenhouse name has been given because glass houses are made of green glass.
Q.76. Assertion: Photochemical smog is produced by oxides of nitrogen.
Reason: Vehicular pollution is a major source of oxides of nitrogen.
Q.77. Assertion: For greenhouse effect, presence of green plants is essential.
Reason: Chlorophyll of the green plants causes greenhouse effect.
Q.78. Assertion: Normal rain water has a pH of about 5.6.
Reason: The pH is due to dissolution of CO2 to form carbonic acid.
Q.79. Assertion: In India, an oil spill occurred in Bombay in 1993.
Reason: Spreading of oil into sea is called oil spill.
Q.80. Assertion: Higher concentration of CO2 in atmosphere is causing global warming.
Reason: This is due to greenhouse effect.
Q.81. Assertion: The presence of CO reduces the amount of haemoglobin available in the. blood for carrying oxygen to the body cells.
Reason: CO combines with haemoglobin about 200 times less easily than oxygen to form complex.
Q.82. Assertion: Photochemical smog is oxidising in nature.
Reason: Photochemical smog contains NO2 and O3, which are formed during the sequences of reactions.
Answers
71. (d) 72. (a) 73. (b) 74. (e) 75. (e) 76. (b) 77. (e)
78. (a) 79. (b) 80. (a) 81. (c) 82. (a)
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