XII Che Assertion

ASSERTION - REASON

Solid State***
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1. Assertion: Crystalline solids have long range orderReason: Amorphous solids have short range orderAns.bQ2Assertion: Glass panes fixed to windows or panes of old buildings are found to be slightly thicker at the bottom.Reason: Amorphous solids have a tendency to flow.Ans.aQ3Assertion: In crystal lattice, the size of the tetrahedral hole is larger than an octahedral hole.Reason: The cations occupy less space than anions in crystal packingAns.dQ4. Assertion: In close packing of spheres, a tetrahedral void is surrounded by four spheres whereas an octahedral void is surrounded by six spheresReason: A tetrahedral void has a tetrahedral shape whereas an octahedral void has an octahedral shape.Ans.cExplanation: Tetrahedral void is so called because it is surrounded by four spheres tetrahedrally while octahedral void is so called because it is surrounded by six spheres octahedrally.Q5.Assertion: The packing efficiency is maximum for the fcc structureReason: The coordination number is 12 in fcc structures.Ans.bQ6. Assertion: In any ionic solid (MX) with schottky defects, the number of positive and negative ions are same.Reason: Equal number of cation and anion vacancies are present.Ans.aExplanation: Schottky defects is due to missing of equal number of cations and anions.Q7. Assertion:Electrical conductivity of semiconductors increases with increasing temperature.Reason: With increase in temperature, large number of electrons from the valence band can jump to the conduction band.Ans.aExplanation: In case of semiconductors, the gap between valence band and the conduction band is small and therefore some of the electrons may jump from valence band to conduction band and thus on increasing temperature conductivity is also increase.Q8Assertion: On heating ferromagnetic or ferrimagnetic substances, they become paramagnetic.Reason: The electrons change their spin on heating.Ans.aExplanation: All magnetically ordered solids (ferromagnetic, ferrimagnetic, and antiferromagnetic solids) transform to the paramagnetic state at high temperature due to the randomisation of spin.---------------------------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.
Q9.Assertion: Covalent crystals have the highest melting point.Reason: Covalent bonds are stronger than ionic bondAns.c.Explanation: Covalent bonds are weaker than ionic bonds. (Higher melting points of covalent crystals are due to network structures)Q10.Assertion: CsCl as body-centred cubic arrangement.Reason: CsCl has one Cs+ ion and 8 Cl- ions in its unit cellAns.c.Explanation: CsCl has one Cs+ ion and one Cl- ions in its unit cell.Q11. Assertion: Hexagonal close packing is more closely packed than cubic close packing.Reason: Hexagonal close packing has a coordination number of 12 whereas cubic close packing has a coordination number of 8.Ans.d.Explanation: Hexagonal close packing and cubic close packing are equally close packed (space occupied = 74%). Both have a coordination number of 12.Q12Assertion: In NaCl crystal, all the octahedral voids are occupied by Na+ ionsReason: The number of octahedral voids is equal to the number of Cl- ions in the packing.Ans. b.Explanation: Na+ ions can be placed only in the octahedral voids (Tetrahedral voids are too small to accommodate them).Q13Assertion: Frenkel defects are shown by silver halides.Reason: Ag+ ions have small size.Ans.aQ14,Assertion: Triclinic system is the most unsymmetrical systemReason: No axial angle is equal to 90* in triclinic system.Ans.bExplanation: Axial angles are not equal to each other.Q15.Assertion: Zinc blende and wurtzite both have fcc arrangement of sulphide ions.Reason: A unit cell of both has four formula units of ZnSAns.dQ16 Assertion: Antiferromagnetic substances on heating to high temperature become paramagnetic.Reason: On heating, randomisation of spins occurs.Ans.aQ17Assertion: Size of the cation is larger in tetrahedral hole than in an octahedral hole.Reason: The cations occupy more space than anions in crystal packing.Ans. d.Q18Assertion: In any ionic solid, {MX}, with Schottky defects, the number of positive and negative ions are same.Reason: Equal number of cation and anion vacancies are present.Ans. a.Q19Assertion: Graphite is an example of tetragonal system.Reason: For a tetragonal system a=b=/=c, alpha = beta = 90*, gamma = 120*.Ans. d.

Solutions***
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1. Assertion: Molarity of a solution in liquid state changes with temperatureReason: The volume of a solution changes with change in temperatureAns.aQ2Assertion: If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e. ps>po Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.Ans.c.Explanation: Both the solute and solvent will form the vapours but vapour phase will become richer in the more volatile component.Q3. Assertion: If one component of a solution obeys Raoult's law over a range of composition, the other component will not obey Henry's law in that range.Explanation:Raoult's law is a special case of Henry's lawAns.b.Q4. Assertion: Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or less than both the components.Reason: The composition of the vapour phase is same as that of the liquid phase of an azeotropic mixture.Ans.bQ5 Assertion: When methyl alcohol is added to water, boiling point of water increases.Reason:When a volatile solute is added to volatile solvent elevation in boiling point is observed.Ans.dQ6 Assertion: When NaCl is added to water a depression in freezing point is observed.Reason: The lowering of vapour pressure of a solution causes depression in the freezing point.Ans.aQ7Assertion:When a solution is separated from the pure solvent by a semi-permeable membrane, the solvent molecules pass through it from pure solvent side to the solution side.Reason: Diffusion of solvent occurs from a region of high concentration solution to a region of low concentration solution.Ans.b
-------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.--------------Q8. Assertion: A solution which contains one gram equivalent of solute per litre of the solution is called normal solution.Reason: A normal solution means a solution in which the solute does not dissociate or associate.Ans.b.Q9Assertion: The sum of mole fractions of all the components of a solution is unity.Reason: Mole fraction is a temperature dependent mode of concentration.Ans.c.Q10. Assertion: Cooking time is reduced in pressure cooker.Reason: Boiling point inside the pressure cooker is raised.Ans.aQ11. Assertion: Van't Hoff factor for benzoic acid in benzene is less than one.Reason: Benzoic acid behaves as a weak electrolyte in benzene.Ans. c.Q12. Assertion: If on mixing the two liquids, the solution becomes hot, it implies that it shows negative deviation from Raoult's law.Reason: Solution which show negative deviation are accompanied by decrease in volume.Ans.b.Explanation: In case of solutions showing negative deviation, the forces of interaction between the components are stronger than those in the pure components.Q13.Assertion: One molar aq solution has always higher conc than one molal solution.Reason: One molar solution contains less solvent than one molal solution.Ans. a.Q14Assertion: The depression in freezing point depends on the amount of the solute dissolved and not on the nature of the solute or solvent.Reason: For aq solutions of different electrolytes, molal depression constant will have different value. Ans. d.Explanation: The depression in freezing points depends upon the nature of the solvent (because different solvents have different value for Kf ). For aq solutions of different electrolytes, Kf is same because solvent is same i.e. water.Q15. Assertion: 0.1 M solution of glucose has higher increment in the freezing point than 0.1M solution of urea.Reason: Kf for both has different values.Ans. d.Explanation: Both being non-electrolytes with same molar conc. will have same decrease (not increment) in freezing point. Both being aq solution i.e. solvent is same (water). Kf will be same for both.Q16.Assertion: Increasing pressure on pure water decrease its freezing point.Reason: Density of water is max at 273KAns. c.Explanation: Density of water is max at 40C or 277.15K.Q17Assertion: The molecular weight of acetic acid determined by depression in freezing point method in benzene and water was found to be different.Reason: Water is polar and benzene is non-polar.Ans. a.Q18.Assertion: if red blood cells were removed from the body an placed in pure water, pressure inside the cells increases.Reason: The conc. of the salt content in the cells increases.Ans.c.Explanation: water enters the cells.

P Block Elements***
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1 Assertion: Dinitrogen is inert at room temperature.Reason: Dinitrogen directly combines with lithium to form ionic nitridesAns.cExplanation: At higher temperatures, dinitrogen combines with metals to form ionic nitridesQ2Assertion:N2 is less reactive than P4Reason: Nitrogen has more electron gain enthalpy than phosphorous.Ans.cQ3Assertion: When a metal is treated with conc HNO3 it generally yields a nitrate, NO2 and H2O.Reason: Conc. HNO3 reacts with metal and first produces a metal nitrate and nascent hydrogen. The nascent hydrogen then further reduces HNO3 to NO2.Ans.aExplanation: Both assertion and reason are true and reason is the correct explanation of assertion.M (metal) + HNO3 (conc.)→ MNO3 + H (nascent hydrogen2HNO3 + 2H (nascent hydrogen)→ 2NO2 + 2H2OQ4Assertion:White phosphorous is more reactive than red phosphorousReason: Red phosphorous consists of P4 tetrahedral units linked to one another to form linear chains.Ans.bExplanation:White phosphorous exists at P4 tetrahedral molecule having P-P-P bond angle 60 degrees. Hence the molecule is under strain and more reactive. On the other hand red phosphorous exists as P4 tetrahedral which are joined together through covalent bonds giving polymeric structure.Q5Assertion:Bond angle of H2S is smaller than H2OReason: Electronegativity of the central atom increases, bond angle decreases.Ans. c.Explanation: Bond angle of H2S 920 < H2O (104031'). As the electronegativity of the central atom decreases, bond angle decreases. In the present case, S is less electronegative than oxygen. Thus bond pairs in H2S are more away from the central atom than in H2O and thus repulsive forces between bond pairs are smaller producing smaller bond angle.Q6Assertion:Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as O2.Reason: Oxygen forms p𝜋-p𝜋 multiple bonding is not possible in sulphurAns. a.Q7Assertion: SF6 cannot be hydrolysed but SF4 can be.Reason:Six F atoms in SF6 prevent the attack of H2O on sulphur atom of SF6.Ans.a.
-------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.--------------Q8. Assertion: H20 is the only hydride of chalcogens which is liquid at ordinary temperatureReason: In ice, each O atom is surrounded by two covalent bonds and two H-bonds.Ans.b.Q9. Assertion: P4 is more reactive than N2.Reason: P-P single bond is much weaker as compared to N=N triple bond.Q10. a.Assertion: F-F bond in F2 molecule is weak.Reason: F atom is small in size.Ans. b. Q11.Assertion: HNO3 renders iron passive.Reason: Iron reacts with HNO3 to form ferric nitrate.Ans. cQ12.Assertion: Xenon forms fluorides.Reason: Because 5d orbitals are available for valence shell expansion.Ans. a.Q13Assertion: The O-O bond length in H2O2 is shorter than that of O2F2.Reason: H2O2 is an ionic compound.Ans.d.Q14Assertion: NF3 is a weak ligand than N(CH3)3Reason: NF3 ionises to give F- ion in aq solutionAns. c.Q15. Assertion: HClO4 is a stronger acid than HClO3.Reason: Oxidation state of Cl in HClO4 is +7 and in HClO3 is +5.Ans. aQ16. Assertion: all F-S-F bond angles in SF4 are greater than 90* but less than 180*.Reason: The lone pair-bond pair repulsion is weaker than bond pair-bond pair repulsion.Ans. cQ17Assertion: Reaction of SO2 and H2S in the presence of Fe2O3 catalyst gives elemental sulphurReason: SO2 is a reducing agent.Ans. cQ18Assertion: SiF6 2- is known but SiCl6 2- is not.Reason: Size of F is small and its lone pair of electrons interact with d-orbitals of Si strongly.Ans. aQ19Assertion: Ozone is a powerful oxidising agent in comparison to O2.Reason: Ozone is diamagnetic but O2 is paramagnetic.Ans.bQ20. Assertion: SeCl4 does not have a tetrahedral structure.Reason: Se in SeCl4 has two lone pairs.Ans. cQ21Assertion Nitrogen is less reactive than molecular oxygen.Reason: The bond length of N2 is shorter than that of oxygen.Ans. a.

Haloalkarenes***
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1.Assertion: SN2 reaction of an optically active aryl halide with an aq solution of KOH always gives an alcohol with opposite sign of rotation.Reason: SN2 reactions always proceed with inversion of configuration.Ans. d.Explanation: Assertion is false,because aryl halides do not undergo nucleophilic substitution under ordinary conditions. This is due to resonance, because of which the carbon-chlorine bond acquires partial double bond character, hence it becomes shorter and stronger and thus cannot be replaced by nucleophiles. However, reason is true.Q2.Assertion: Alkylbenzene is not prepared by Friedel-Crafts alkylation of benzene.Reason: Alkyl halides are less reactive than acyl halides.Ans.c.Explanation: alkyl halides give polyalkylation products.Q3.Assertion: Exposure of UV rays to human causes the skin cancer, disorder and disrupt the immune system.Reason: Carbon tetrachloride is released into air it rises to atmosphere and depletes the ozone layer.Ans. b.Explanation: Carbon tetrachloride rises to atmosphere and deplete the ozone layer. This depletion of ozone layer increases exposure of UV rays to human being which lead to increase of skin cancer, eye diseases and disorder with disruption of the immune system.Q4.Assertion:CHCl3 is stored in dark bottles.Reason:CHCl3 is oxidised in dark.Ans.c.Explanation: CHCl3 is stored in dark bottles to prevent oxidation of CHCl3 in presence of sunlight.Q5.Assertion:CCl4 is not a fire extinguisherReason:CCl4 is insoluble in water.Ans.d.Explanation: CCl4 is used as a fire extinguisher. The dense, non combustible vapours cover the burning substance and prevents the availability of oxygen around burning material.
-------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.--------------Q6Assertion: p-Dichlorobenzene is less soluble in organic solvents than the corresponding o-isomer.Reason: o-Dichlorobenzene is polar while p-Dichlorobenzene is non-polar.Ans.bExplanation: p-Dichlorobenzene fit closely in the crystal lattice.Q7.Assertion: tert-Butyl chloride on treatment with sodium metal in dry ether gives 2,2,3,3,-tetramethyl butane.Reason:tert-Alkyl halides readily undergo Wurtz reactionAns.dExplanation: tert-Butyl chloride on treatment with Na metal gives no-butane and isobutylene. tert-alkyl halides do not undergo Wurtz reaction. Q8.Assertion: Alkyl halides are not soluble in waterReason: Although polar in nature yet alkyl halides are not able to form H-bonds with water molecules.Ans.aQ9Assertion: Chlorobenzene is less reactive than chloroethane towards nucleophilic substitution reactions.Reason: The forces of attraction between alkyl halide and water molecules are weaker than those present in between molecules of alkyl halides and water molecules separately.Ans. bExplanation: Due to resonance, C-Cl bond in chlorobenzene is little stronger than C-Cl in chloroethane.Q10. Assertion: In comparison to ethyl chloride, it is difficult to carry out nucleophilic substitution on vinyl chlorideReason: Vinyl group is electron-donating.Ans.cExplanation: The carbon-halogen bond has some double bond character.Q11. Assertion: Methylmagnesium iodide should be prepared under perfectly anhy conditions.Reason: Grignard reagents readily react with water.Ans. aQ12.Assertion: SN2 reactions proceed with inversion of configurationReason: SN2 reactions occur in one stepAns. bExplanation: The attack of nucleophile occurs from a side opposite to the halogen atomQ13.Assertion: 1-Butene on reaction with HBr in the presence of a peroxide produces 1-bromobutane.Reason: It involves formation of a primary alcohol.Ans.c.Explanation: The reaction occurs through the formation of a more stable 2* free radical.Q14 Assertion: Benzyl bromide when kept in acetone - water it produces benzyl alcohol.Reason: The reaction follows SN2 mechanismAns.cExplanation: Benzyl halides undergo hydrolysis by SN1 mechanismQ15Assertion Hydroxy ketones are not directly used in Grignard reaction.Reason: Grignard reagents react with hydroxyl groupAns. aQ16Assertion: 2-Bromobutane on reaction with sodium ethoxide in ethanol gives 1-butene as a major product.Reason: 1-Butene is more stable than 2-butene.Ans. dExplanation: 2-Bromobutane on reaction with sodium ethoxide in ethanol gives 2-butene as the major. 2-Butene is more stable than butene.Q17Assertion: Rate of hydrolysis of methyl chloride to methanol is higher in DMF than in water.Reason: Hydrolysis of methyl chloride follows second order kineticsAns. aExplanation: DMF is a polar aprotic solvent i.e. does not contain any OH group while H2O is a polar protic solvent. Therefore, nucleophile, i.e. OH- ion is solvated in H2O but not in DMF. As a result, the OH- ion is more nucleophilic in DMF than in H2O and hence the rate of the reaction increases.Q18 Assertion: The presence of nitro group facilitates nucleophilic substitution reaction in aryl halides.Reason: THe intermediate carbanion is stabilized due to the presence of the nitro-groupAns.aQ19Assertion: Diastereomers have different physical properties.Reason: They are non-superimposable mirror images.Ans. c.Explanation: Diastereomers are not mirror imagesQ20 Assertion: Addition of HBr to 2-butene gives two isomeric productsReason: Addition of HBr to 2-butene follows Markonikov's rule.Ans. dExplanation: Addition of HBr to 2-butene gives only a single product. Addition of HBr to 2-butene does not follow Markonikov's rule. Symmetrical alkenes do not follow Markonikov's rule.Q21Assertion: Chloral reacts with phenyl chloride to form DDTReason: It is an electrophilic substitution reaction.Ans. aQ22Assertion: Alkyl iodide can be prepared by treating alkyl chloride / bromide with NaI in acetone.Reason: NaCl/ NaBr are soluble in acetone while NaI is not.Ans.cExplanation: NaCl/ NaBr are insoluble in acetone while NaI is soluble.

Alcohols***
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1. Assertion: The bond angle in alcohols is slightly less than the tetrahedral angle.Reason: In alcohols, the oxygen of -OH group is attached to sp3 hybridised carbon atom.Ans.Q2Assertion: In Lucas test, 3 degree alcohol reacts immediately.Reason: An equimolar mixture of anhy. ZnCl2 and conc. HCl is called Lucas reagent.Q3. Assertion: Riemer-Tiemann reaction of phenol with CCl4 in NaOH at 340K gives salicylic acid as the major product.Reason: The reaction occurs through intermediate formation of dichlorocarbene.Q4.Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction.Reason: In the case of phenol, the intermediate carbocation is more resonance stabilized.Ans.Q5. Assertion: In case of phenol, bromination takes place even in absence of Lewis and whereas bromination of benzene takes place in presence of Lewis acid like FeBr3Reason: -OH group attached to benzene ring is highly deactivating.Q6.Assertion: tert-Butyl methyl ether is not prepared by the reaction of tert-Butyl bromide with sodium methoxide.Reason: Sodium methoxide is a strong nucleophile.Ans.Q7.Assertion: Ethers behave as bases in the presence of mineral acids.Reason: Due to the presence of lone pairs of electrons on oxygen.Ans.aQ8. Assertion: with HI, anisole gives iodobenzene and methyl alcohol.Reason: Iodide ion combines with smaller group to avoid steric hindrance.Ans.dQ9.Assertion: with HI at 373K, tert-Butyl methyl ether gives tert-Butyl iodide and methanol.Reason: The reaction occurs by SN2 mechanism.Ans.cQ10.Assertion: Ethyl phenyl ether on reaction with HBr form phenol and ethyl bromide.Reason: Cleavage of C-O bond takes place on ethyl-oxygen bond due to the more stable phenyl-oxygen bond.Ans.c.Explanation: Alkyl aryl ethers are cleaved at the alkyl -oxygen bond due to the more stable aryl-oxygen bond. The reaction yields phenol and alkyl halide.
C6H5-O-R + HX = Phenol + RXEtheres with two different alkyl groups are also cleaved in the same mannerR-o-R' + HX = RX + R'-OH
-------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.--------------Q11.Assertion: p-Dichlorobenzene is less soluble in organic solvents than the corresponding o-isomer.Reason: o-Dichlorobenzene is polar while p-Dichlorobenzene is non-polar.Ans.bExplanation: p-Dichlorobenzene fit closely in the crystal lattice.Q12.Assertion: tert-Butyl chloride on treatment with sodium metal in dry ether gives 2,2,3,3,-tetramethyl butane.Reason:tert-Alkyl halides readily undergo Wurtz reactionAns.dExplanation: tert-Butyl chloride on treatment with Na metal gives no-butane and isobutylene. tert-alkyl halides do not undergo Wurtz reaction. Q13.Assertion: Alkyl halides are not soluble in waterReason: Although polar in nature yet alkyl halides are not able to form H-bonds with water molecules.Ans. a

Biomolecules
(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) Assertion is false but reason is true.
Q1.Assertion: D(+)-Glucose is dextrorotatory in nature.Reason: D represents its dextrorotatory nature.Ans.cQ2Assertion: Sucrose is called an invert sugarReason: On hydrolysis, sucrose bring the change in the sign of rotation from dextro(+) to laevo(-).Ans.aExplanation: The hydrolysis of sucrose brings about a change in the sign of rotation from dextro (+) to laevo (-) and the product is named as invert sugar.Q3Assertion: beta-glycosidic linkage is present in maltose.Reasons: Maltose is composed of two glucose units in which C-1 of one glucose unit is linked to C-4 of another glucose unit.Ans.dExplanation: Maltose is the compound of the two alpha-D-glucose units in which C1 of one glucose is linked to C4 of another glucose unit.Q4.Assertion: At isoelectric point, the amino group does not migrate under the influence of electric field.Reason: At isoelectric point, amino acid exists as a zwitterion.Ans.aQ5Assertion: Vitamin D cannot be stored in the body.Reason: Vitamin D is fat soluble vitamin and is excreted from the body in urine.Ans.d.Explanation: Vitamin D is a fat soluble vitamin and can be stored in the body since it is not excreted out of the body.-------------(a) Both assertion and reason are true and the reason is the correct explanation of assertion.(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.(c) Assertion is true but reason is false.(d) If both Assertion and reason are false.--------------Q6Assertion: C2H5OH is a weaker acid than phenol but is a stronger nucleophile than phenolReason: In phenol the lone pair of electrons on oxygen is withdrawn towards the ring due to resonance.Ans. aQ7Assertion:Neopentyl alcohol on treatment with HCl gives neopentyl alcoholReason:Neopentyl is a tertiary alcoholAns.d.Explanation: Neopentyl alcohol on treatment with HCl gives 2-chloro-2-methylbutane and not neopentyl alcohol. This reaction occurs via rearrangement of initially formed less stable 1* carbocation to the more stable 3* carbocation.Q8Assertion: Phenol forms 2,4,6-tribromophenol on treatment with excess bromine water.Reason:2,4,6-tribromophenol is less soluble in water than phenol.Ans.bQ9Assertion: a mixture of 2-nitrophenol and 4-nitrophenol can be separated by steam distillation.Reason:2-Nitrophenol is intramolecularly hydrogen bonded while 4-nitrophenol is intermolecularly hydrogen bonded. Ans.aQ10Assertion: The boiling points of alcohols are higher than those of hydrocarbons of comparable molecular mass.Reason: Alcohols show intramolecular hydrogen bonding.Ans.cQ11Assertion: The boiling point of ethanol is much higher than that of diethyl ether. Reason:In ethanol, the molecules are associated by the formation of intermolecular hydrogen bonding where in diethyl ether it is not possible.Ans. aQ12Assertion: Traces of moisture from phenol can be easily removed by distilling with sodium metal. Reason: Water is more acidic than phenol.Ans. d.Q14Assertion: Phenol undergoes Kolbe's reaction but ethanol does not. Reason:Phenoxide ion is more basic than ethoxide ion.Ans. cQ15Assertion: Solubility of n-alcohols in water decreases with increase in molecular massReason: The relative proportion of the hydrocarbon part in alcohols increases with increasing molecular mass which permits enhanced hydrogen bonding with water.Ans. cQ16Assertion: p-Nitrophenol is a stronger acid than o-NitrophenolReason: Intramolecular hydrogen bonding makes o-isomer weaker than p-isomer.Ans.aQ17Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction. Reason: In case of phenol, the intermediate carbocation is more resonance stabilized. Ans.aQ18Assertion: Hydroxy ketones are not directly used in Grignard reaction.Reason:Grignard reagents react with hydroxyl group.Ans. aQ19Assertion: The boiling point of ethanol is much higher than that of diethyl ether. Reason: In ethanol, the molecules are associated by the formation of intermolecular hydrogen bonding whereas in diethyl ether it is not possible.Ans. aQ20Assertion: Ethers behave as bases in the presence of mineral acids.Reason: Due to the presence of lone pairs of electrons on oxygen.Ans. aQ21Assertion: tert-Butyl methyl ether on treatment with HI at 373K gives a mixture of methyl iodide and tert-Butyl alcohol. Reason: The reaction occurs by SN2 mechanism.Q22Assertion: Addition of C2H5OH to 3,3-dimethyl-1-butene in presence of sulphuric acid gives 2-ethoxy-2,3-dimethyl butane instead of 3-ethoxy-2,2-dimethylbutane.Reason: The reaction occurs by SN2 mechanism.Ans. cQ23Assertion: The C-O-C bond angle in ethers is higher than H-O-H angle in water.Reason: Oxygen is sp3 hybridized in both ethers and water.Ans. bQ24Assertion: The major products formed by heating C6H5CH2-O-CH3 with HI are C6H5-CH2-I and CH3-OH.Reason: Benzyl cation is more stable than methyl cation.Ans.aQ25Assertion: t-Butyl methyl ether is not prepared by the reaction of t-butyl bromide with sodium methoxide. Reason: Sodium methoxide is a strong nucleophile.Ans. bExplanation: In presence of a strong base, i.e. sodium methoxide, t-butyl bromide undergoes dehydrohalogenation to form isobutylene.Q26Assertion: The presence of nitro group facilitates nucleophilic substitution reaction in aryl halides. Reason: The intermediate carbanion is stabilized due to the presence of the nitro group.Ans. aQ27Assertion: Benzenediazonium chloride on boiling with water gives phenol. Reason: C-N Bond is polar.Ans. b.Q28Q29Q30Q31

Google Sites

Report abuse