Question

Read the passage given below and answer the following questions: Phenol contains -OH group directly attached to carbon atoms of an aromatic system \(C_6\)\(H_5\)OH in phenol the group is attached to \(sp^2\) hybridised carbon of aromatic ring. The carbon oxygen bond length is 1:36 pm in phenol is slightly less than that in in methanol this is due to first point partial double bond character on account of the conjugation of unshared electron pair of oxygen with the aromatic ring s point \(sp^3\) hybridised state of carbon to which oxygen is attached it can be prepared by various means or methods. Some important methods are alkali fusion of sulphonates, hydrolysis of diazonium salts decarboxylation of salicylic acid and from Grignard reagent, it is prepared from Dow's process and from cumene. Aerial oxidation of human produce cumene peroxide which on hydrolysis produce phenol and acetone. In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (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. (i) Assertion: C-O bond length in phenol is less than C-O bond length in ethanol. Reason: In phenol carbon atom is \(sp^2\) hybridize while in ethanol carbon atom is \(sp^3\) hybridised. (ii) Assertion: p-nitrophenol is more acidic than phenol. Reason: Nitro group helps in the stabilisation of the phenoxide ion by dispersal of negative charge due to resonance. (iii) Assertion: Phenol is prepared by the reaction of chlorobenzene with caustic soda at 623K and 300 atm pressure. Reason: The substitution of chorine atom from chlorobenzene is difficult due to resonance. (iv) Assertion: Methanol is less acidic than phenol. Reason: Due to resonance phenate ion become more stable. (v) Assertion: On nitration phenol forms 2-nitrophenol and 4- nitrophenol. Reason: The presence of –OH group in phenols activates the aromatic ring towards electrophilic substitution and directs the incoming group to ortho and para positions.

Read the passage given below and answer the following questions: Nucleophilic substitution reactions are of two types; substitution nucleophilic bimolecular (SN2) and substitution nucleophilic unimolecular (SN1) depending on molecules taking part in determining the rate of reaction. Reactivity of alkyl halide towards SN1 and SN2 reactions depends on various factors such as steric hindrance, stability of intermediate or transition state and polarity of solvent. SN2 reaction mechanism is favoured mostly by primary alkyl halide or transition state and polarity of solvent, SN2 reaction mechanism is favoured mostly by primary alkyl halide then secondary and then tertiary. This order is reversed in case of SN1 reactions. (i) Which of the following is most reactive towards nucleophilic substitution reaction? (a) \(C_6\)\(H_5\)Cl (b) \(CH_2\)=CHCl (c) \(ClCH_2\)\(CH=CH_2\) (d) \(CH_3\)CH=CHCl (ii) Isopropyl chloride undergoes hydrolysis by (a) SN1 mechanism (b) SN2 mechanism (c) SN1 and SN2 mechanism (d) neither SN1 nor SN2 mechanism (iii) Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of (a) insolubility (b) instability (c) inductive effect (d) steric hindrance (iv) Which of the following is the correct order of decreasing SN2 reactivity? (a) \(RCH_2\)X > \(R_2\)CHX > \(R_3\)CX (b) \(R_3\)CX > \(R_2\)CHX > \(RCH_2\)X (c) \(R_2\)CHX > \(R_3\)CX > \(RCH_2\)X (d) \(RCH_2\)X > \(R_3\)CX > \(R_2\)CHX (v) An organic molecule necessarily shows optical activity if it- a) contains asymmetric carbon atoms b) is non-polar c) is non-superimposable on its mirror image d) is superimposable on its mirror image

Group 18 elements are called noble gases and not inert gases because compounds of Kr, Xe and Rn have been prepared. Their general electronic configuration is \(ns^2\)\(np^6\) except He(\(1s^2\) ). They have highest ionisation enthalpy and positive electron gain enthalpy due to stable electronic configuration. Helium is found in sun and stars. Noble gases have low boiling points due to weak van der Waals’ forces of attraction. Xenon forms \(XeF_2\), \(XeF_4\), \(XeF_6\), \(XeOF_4\), \(XeO_3\), \(XeO_2\)\(F_2\), their structures can be drawn on bases of VSEPR theory. Helium is mixed with oxygen by deep sea divers to avoid pain. Neon is used in coloured advertising lights. Argon is used in bulbs as inert gas. Kr and Xe are used in high efficiency lamps, head light of cars. Radon is radioactive formed by a-decay of Radium 226 88Ra Argon is most abundant (0.9%) noble gas in atmosphere. The following questions are multiple choice questions. Choose the most appropriate answer. 1) What are the elements in group 18 (the far right) of the periodic table called? a) Alkali metals b) Alkaline earth metals c) Halogens d) Noble gases 2) Out of (i) \(XeO_3\) (ii) \(XeOF_4\) and (iii) \(XeF_6\) , the molecules having the same number of lone pairs on Xe are - a) (i) and (ii) only b) (i) and (iii) only c) (ii) and (iii) only d) (i) , (ii) and (iii) 3) Which one has linear shape? a) \(XeF_2\) b) \(XeF_4\) c) \(XeF_6\) d) \(XeO_3\) 4) Which of the outer electronic configuration represent Argon? a) \(ns^2\)\(np^4\) b) \(ns^2\)\(np^3\) c) \(ns^2\)\(np^6\) d) \(ns^1\)\(np^6\) 5) Which of the following statement is false? a) Radon is obtained from the decay of radium b) Helium is an inert gas c) Xenon is the most reactive among the rare gases d) The most abundant rare gas found in the atmosphere is helium

Read the passage given below and answer the following questions: Alkyl halides are prepared by the free radical halogenation of alkanes, addition of halogen acids to alkenes, replacement of -OH group of alcohols with halogens using phosphorus halides, thionyl chloride or halogen acids. Aryl halides are prepared by electrophilic substitution to arene. Fluorine and iodides are best prepared by halogen exchange method. These compounds find wide applications in industry as well as in day-to-day life. These compounds are generally used as solvents and as starting material for the synthesis of a large number of organic compounds. (i) The best method for the conversion of an alcohol into analkyl chloride is by treating the alcohol with (a) \(PCl_5\) (b) dry HCl in the presence of anhydrous \(ZnCl_2\) (c) \(SOCl_2\) in presence of pyridine (d) None of these (ii) The catalyst used in the preparation of an alkyl chloride bythe action of dry HCl on an alcohol is (a) anhydrous \(AlCl_3\) (b) \(FeCl_3\) (c) anhydrous \(ZnCl_2\) (d) Cu (iii) An alkyl halide reacts with metallic sodium in dry ether. The reaction is known as : (a) Frankland’sreaction (b) Sandmeyer’sreaction (c) Wurtz reaction (d) Kolbe’s reaction (iv) Fluorobenzene (\(C_6\)\(H_5\)F) can be synthesized in the laboratory (a) by direct fluorination of benzene with \(F_2\) gas (b) by reacting bromobenzene with NaF solution (c) by heating phenol with HF and KF (d) from aniline by diazotisation followed by heating thediazonium salt with \(HBF_4\) (v) When 2-bromobutane reacts with alcoholic KOH, thereaction is called (a) halogenation (b) chlorination (c) hydrogenation (d) dehydrohalogenation

Read the passage given below and answer the following questions: In an ideal crystal, there must be regular repeating arrangement of the constituting particles and its entropy must be zero at absolute zero temperature. However, it is impossible to obtain an ideal crystal and it suffers from certain defects called imperfections. In pure crystal, these defects arises either due to disorder or dislocation of the constituting particles from the normal positions or due to the movement of the particles even at absolute zero temperature. Such defects increase with rise in temperature. In addition to these certain defects arise due to the presence of some impurities. Such defects not only modify the existing properties of the crystalline solids but also impart certain new characteristics to them. Answer the following MCQs by choosing the most appropriate options: 1) AgCl is crystallized from molten AgCl containing a little \(CdCl_2\). The solid obtained will have (a) cationic vacancies equal to number of \(Cd^{2+}\) ions incorporated. (b) cationic vacancies equal to double the number of \(Cd^{2+}\) ions. (c) anionic vacancies. (d) neither cationic nor anionic vacancies. 2) Lattice defect per \(10^{15}\) NaCl is 1. What is the number of lattice defects in a mole of NaCl? (a) 6.02 × \(10^{23}\) (b) 6.02 × \(10^8\) (c) \(10^{14}\) (d) None of these 3) The ionic substances in which the cation and anion are of almost similar size shows (a) non-stoichiometric defect (b) Schottky defect (c) Frenkel defect (d) all of these 4) Which of the following gives both Frenkel and Schottky defect? (a) AgCl (b) CsCl (c) KCl (d) AgBr

The properties of dilute or ideal solutions which depend only upon the concentration of the solute in the solution and no other characteristics are known as colligative properties. There are in all four such properties i.e. relative lowering in vapour pressure, osmotic pressure, elevation in boiling point temperature and depression in freezing point temperature. All of them help in calculating the observed molar mass of the solute which is inversely proportional to the colligative property involved. Out of these, osmotic pressure may be regarded as the best for the determination of molecular mass of the solute. According to Van’t Hoff theory of dilute solution, π = CRT, where ‘π’ is the osmotic pressure while ‘C’ is the molar concentration of the solution. (i) When liquids A and B are mixed, hydrogen bonding occurs. The solutions will show: a) Positive deviation from Raoult’s law b) Negative deviation from Raoult’s law c) No deviation from Raoult’s law d) Slightly increase in volume (ii) The azeotropic mixture of water and HCl boils at \(108.5^\circ\)C when the mixture is distilled. It is possible to obtain: a) Pure HCl b) Pure water c) Pure water as well as pure HCl d) Neither HCl nor water in their pure states. (iii) On freezing an aqueous solution of sugar, the solid which starts separating out is: a. Sugar b. Ice c. Solution with the same composition d. Solution with different composition (iv) The value of osmotic pressure does not depend upon: a) Concentration of the solution b) Temperature of the solution c) Number of the particles of the solute present d) Structure of the solute particles (v) Effect of adding a non-volatile solute to a solvent is : a) to lower the vapour pressure b) to increase the freezing point c) to decrease the boiling point d) to decrease the osmotic pressure

Read the passage given below and answer the following questions: All real structures are three-dimensional structures. They can be obtained by stacking two dimensional layers one above the other while placing the second square close packed layer above the first we follow the same rule that was followed when one row was placed adjacent to the other. The second layer is placed over the first layer such that the spheres of the upper layer are exactly above there of the first layer. In his arrangement spheres of both the layers are perfectly aligned horizontally as well as vertically. A metallic element crystallise into a lattice having a ABC ABC pattern and packing of spheres leaves out voids in the lattice. 1) What type of structure is formed by this arrangement? (A) ccp (B) hcp (C) ccp/fcc (D) none of the above 2) Name the non-stoichiometric point defect responsible for colour in alkali metal halides. (A) Frenkel defect (B) Interstitial defect (C) Schottky defect (D) F-centres 3) What is the total volume of atoms in a face centred cubic unit cell of a metal? (r is atomic radius). (A) 16/3 \(πr^3\) (B) \(πr^3\) (C) 24/3 \(πr^3\) (D) 12/3 \(πr^3\) 4) Which of the following statements not true for the amorphous and crystalline solids? (A) Amorphous solids are isotropic and crystalline solids are anisotropic. (B) Amorphous solids are short range order and crystalline solids are long range order. (C) Amorphous solids melt at characteristic temperature while crystalline solids melt over a range of temperature. (D) Amorphous solids have irregular shape and crystalline solids have a geometrical shape.