Description : Alcohols are easily protonated than phenols. Justify.
Last Answer : Ans. In phenols lone pair of electrons on the oxygen atom are delocalised over the benzene ring due to resonance and hence are not easily available for protonation. In contrast in alcohols, ... oxygen atom are localized due to absence of resonance and hence are easily available for protonation.
Description : Phenols do not undergo substitution of the — OH group like alcohols. Explain.
Last Answer : The C — O bond in phenols has some double bond character due to resonance and hence cannot be easily cleaved by a nucleophile. In contrast, the C — O bond in alcohols is a pure single bond and hence can be easily cleaved by a nucleo phile.
Description : While separating a mixture of ortho and para-nitro phenols by steam distillation, name the isomer which will be steam volatile. Give reasons.
Last Answer : In o-nitrophenol, there is intramolecular hydrogen bonding as follows : In p-nitrophenol, there is intramolecular hydrogen bonding as follows : Due to intermolecular H ... -nitrophenol. Hence o-nitraphenol due to its lower b. p. is steam volatile while pnitrophenol is not.
Description : Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?
Last Answer : 1. Once the oxidation has reached the ketone stage, (primary alcohols on oxidation yield aldehyde where as secondary alcohols on oxidation yield a ketone), it is impossible to put more oxygen atoms on the relevant carbon atom without rupturing the backbone of the molecule.
Description : Alcohols acts as weak bases. Explain.
Last Answer : The oxygen atom of the hydroxyl group has two lone pairs of electrons. Therefore alcohols accept a proton from strong mineral acid to form oxonium ions. Hence act as weak bases.
Description : Why phenol is acidic ?
Last Answer : Ans: In phenol dissociation takes place as follows. The conjugate base of phenol ie. Phenoxide ion is resonance stabilized. This is why the negative charge on oxygen atom is ... ion has less tendency to form undissociated phenol molecule and equilibrium lies towards right direction.
Description : Ortho and paranitrophenols are more acidic than phanel. Draw the resonance structures of the corresponding phonoxide ion.
Last Answer : Ans:- Electronwithdrawal by nitro group makes the plenoxide ion more resonance stabilized and so the strength of phenel increases.
Description : Ethers are cleaved by acids not by based. Why ?
Last Answer : The C - O - C bond in ethers like the C - OH bond in alcohols is quite strong. In order to weaken it, the oxygen atom must be protonated. A subsequent nucleophile attack by a strong ... protonation of O atom of ether and therefore only acids can bring about the cleavage of ethers and not bases.
Description : How an — OH group attached to carbon in the benzene ring activates benzene towards electrophilic substitution ?
Last Answer : The lone pair of electrons present on oxygen atom enter into resonance with the benzene ring. As a result, the electron density becomes higher at o- and p- position and due to higher electron density, the ring gets activated towards electrophilic substitution.
Description : Di-tert butyl ether cannot be made by Williamson’s synthesis. Explain why ?
Last Answer : Ans. To prepare di tert-butyl ether by Williamson's synthesis, we need tert-butyl bromide and Sodium tertiary butoxide. Since tert-butyl bromide being 3°-alkyl halide prefers to ... rather than substitution, therefore the product obtained is isobutylene rather than ditertiary butyl ether.
Description : Why are Grignard reagents soluble in ether but not in benzene ?
Last Answer : Ans. Grignard reagents from co-ordination complexes with ether but not benzene since the former has lone pair of electrons but the later does not.
Description : Name the products obtained when anisole is treated with HI.
Last Answer : Ans. Phenol and methyl iodide.
Description : What is usually added to ethyl alcohol to make it unfit for drinking purposes ?
Last Answer : Ans. Methanol and Pyridine.
Description : What is the main product obtained when vapours of t-butyl alcohol are passed over copper at 300° ?
Last Answer : Ans. Isobutylene (2-Methyl propene)
Description : Phenols can be easily distinguished from alcohols because (a) phenols are soluble in NaOH, but alcohols are not (b) alcohols are soluble in NaOH, but phenols are not (c) phenols are soluble in NaHCO3, but alcohols are not (d) alcohols are soluble in NaHCO3, but phenols are not
Last Answer : phenols are soluble in NaOH, but alcohols are not
Description : Which group forms the strongest H-bonds to water molecules? (a) Alcohols (b) Ethers (c) Phenols (d) All equally strong
Last Answer : Phenols
Description : Assertion : Phenols are more acidic than aliphatic alcohols. Reason : Phenoxides are stabilized by resonance.
Last Answer : Assertion : Phenols are more acidic than aliphatic alcohols. Reason : Phenoxides are stabilized by resonance. ... D. A is incorrect but R is correct
Description : The best definition of polarisation is a) Orientation of dipoles in random direction b) Electric dipole moment per unit volume c) Orientation of dipole moments d) Change in polarity of every dipole
Last Answer : b) Electric dipole moment per unit volume
Description : Which of the following would be most acidic? w) phenol x) methanol y) acetic acid z) methyl amine
Last Answer : ANSWER: C -- ACETIC ACID
Description : The 1936 Nobel Prize in chemistry was awarded to Peter J.W. Debye for his studies of: w) kinetic energy of colliding particles x) electron configuration y) dipole moments z) conformations of cyclohexane
Last Answer : ANSWER: Y -- DIPOLE MOMENTS
Description : Which one of the following raw material is used in the manufacture of foam used in mattresses cushions etc. A. Phenol B. Urea C. Methanol D. Ethanol
Last Answer : ANSWER: A
Description : In sweetening process, solutizer agent used with caustic alkali is (A) Potassium isobutyrate (B) Sodium plumbite (C) Methanol (D) Phenol
Last Answer : (A) Potassium isobutyrate
Description : The total polarisation of a material is the a) Product of all types of polarisation b) Sum of all types of polarisation c) Orientation directions of the dipoles d) Total dipole moments in the material
Last Answer : b) Sum of all types of polarisation
Description : Dipole moments are used to calculate the a) Electric field intensity b) Polarisation patterns c) Strength of the dipole in the field d) Susceptibility
Last Answer : b) Polarisation patterns
Description : The statement that is NOT correct is (a) The breaking of complex and big molecules into simpler and smaller molecules by micro-organisms is called fermentation. (b) Whisky contains high ... d) Alcoholic fermentation involves the conversion of sugars into alcohol by the use of micro-organisms.
Last Answer : Ans:(b)
Description : Which of the following compounds has maximum dipole moment? (a) p-Dichlorobenzene (b) m-Dichlorobenzene (c) o-Dichlorobenzene (d) Carbon tetrachloride
Last Answer : o-Dichlorobenzene
Description : The pH at which the amino acid shows no tendency to migrate when placed in an electric field is known as its : (a) Isoelectric point (b) Dipole moment (c) Iodine number (d) Wavelength
Last Answer : Isoelectric point
Description : Which of the following compounds will have zero dipole moment? (a) cis-1,2-dibromoethylene (b) 1,1-dibromoethylene (c) trans-1,2-dibromoethylene (d) all of these
Last Answer : trans-1,2-dibromoethylene
Description : Which of the following compounds have highest dipole moment? (a) dichloromethane (b) chloroform (c) chloromethane (d) carbon tetrachloride
Last Answer : dichloromethane
Description : Which molecule has the greatest dipole moment (a) CH3Cl (b) CH3Br (c) CH3F (d) CH3I
Last Answer : CH3F
Description : Which of the following compounds have lowest dipole moment? (a) carbon tetrachloride (b) chloromethane (c) dichloromethane (d) chloroform
Last Answer : carbon tetrachloride
Description : Which molecule has a nonzero dipole moment? (a) Cl2 (b) CO2 (c) CCl4 (d) CHCl3
Last Answer : CHCl3
Description : Which of the following compounds will show dipole moment? (a) cis-1,2-dichloroethylene (b) o-dichlorobenzene (c) trans-1,2-dichloroethylene (d) p-dichlorobenzene
Last Answer : cis-1,2-dichloroethylene o-dichlorobenzene
Description : Which of the following molecules has a permanent electric dipole moment? w) H2O x) Cl2 y) CH4 z) N2
Last Answer : ANSWER: W -- H2O
Description : Which of the following molecules has a dipole moment? w) BF3 x) NH3 y) CCL4 z) CH4
Last Answer : ANSWER: B -- NH3
Description : Which of the following molecules does NOT have a dipole moment of zero? w) BeCl2 x) BF3 y) CO2 z) NH3
Last Answer : ANSWER: Z -- NH3
Description : Which one of the following compounds form zwitterions? (a) carbonyl compounds (b) amino acids (c) phenols (d) heterocyclic compounds
Last Answer : amino acids
Description : James May discovers the true source of the Nile. Will you take a few moments to celebrate this historic moment in historic history?
Last Answer : answer:Yes. I shall. I was going to say more, but I think it’s all done now,.
Description : The moment of a force is a.Equivalent to the algebraic sum of the moments acting on a body b.Equivalent to the sum of horizontal as well as vertical components of the moments on a body c.Equivalent ... of the moments on a body e.Equivalent to the vertical sum of the moments acting on a body
Last Answer : a. Equivalent to the algebraic sum of the moments acting on a body
Description : An Athlets runs before long jump to get advantage on – (1) Inertia of motion (2) Frictional force (3) Moment of a force (4) Principle of moments
Last Answer : (1) Inertia of motion Explanation: An athlete does so to build up forward momentum so that when he jumps he already has a forward motion that would be greater than that of a jump made from standing in ... in terms of inertia of motion which is the tendency of an object to resist a change in motion.
Description : The location of centre of pressure, which defines the point of application of the total pressure force on the surface, can be calculated by applying the principle of moments according to which "sum of the moment of the resultant force about an ... liquid) (A) 1/(y/3) (B) 2y/3 (C) 1/(y/4) (D) 3y/4
Last Answer : (B) 2y/3
Description : If Ix and Iy are the moments of inertia of a section about X and Y axes, the polar moment of inertia of the section, is (A) (IX + IY)/2 (B) (IX - IY)/2 (C) IX + IY (D) (IX/IY)
Last Answer : (C) IX + I
Description : While using three moments equation, a fixed end of a continuous beam is replaced by an additional span of (A) Zero length (B) Infinite length (C) Zero moment of inertia (D) None of the above
Last Answer : (A) Zero length
Description : The algebraic sum of moments of the forces forming couple about any point in their plane is (A) Equal to the moment of the couple (B) Constant (C) Both of above are correct (D) Both of above are wrong
Last Answer : (A) Equal to the moment of the couple
Description : According to principle of moments (A) If a system of coplanar forces is in equilibrium, then their algebraic sum is zero (B) If a system of coplanar forces is in equilibrium, then the ... of their resultant about the same point (D) Positive and negative couples can be balanced
Last Answer : (C) The algebraic sum of the moments of any two forces about any point is equal to moment of their resultant about the same point
Description : A bending moment may be defined as: (A) Arithmetic sum of the moments of all the forces on either side of the section (B) Arithmetic sum of the forces on either side of the section (C) Algebraic sum of the moments of all the forces on either side of the section (D) None of these
Last Answer : (C) Algebraic sum of the moments of all the forces on either side of the section
Description : Two coplanar couples having equal and opposite moments (A) Balance each other (B) Produce a couple and an unbalanced force (C) Are equivalent (D) Produce a moment of couple
Last Answer : (D) Produce a moment of couple
Description : A vertical column has two moments of inertia (i.e. Ixx and Iyy ). The column will tend to buckle in the direction of the (a) axis of load (b) perpendicular to the axis of load (c) maximum moment of inertia (d) minimum moment of inertia
Last Answer : (d) minimum moment of inertia
Description : A shaft is said to be in pure torsion if a. Turning moment is applied at one end and other end is free b. Turning force is applied at one end and other end is free c. Two opposite turning moments are applied to the shaft d. Combination of torsional load and bending load is applied to the shaft
Last Answer : c. Two opposite turning moments are applied to the shaft
Description : An athlete runs before long jump to get advantage on (1) Inertia of motion (2) Frictional force (3) Moment of a force (4) Principle of moments
Last Answer : Inertia of motion