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Alcohols, Phenols, and Ethers — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryAlcohols, Phenols, and Ethers4 Marks
Question

Read the passage given below and answer the following questions:

Although chlorobenzene is inert to nucleophilic substitution, however it gives quantitative yield of phenol when heated with aq. Na OH at high temperature and under high pressure. As far as electrophilic substitution in phenol is concemed the — OH group is an activating group, hence, its presence enhances the electrophilic substitution at o - and p - positions.

The following questions are multiple choice questions. Choose the most appropriate answer:

  1. Conversion of chlorobenzene into phenol involves:
  1. Modified SN1 mechanism.
  2. Modified SN2 mechanism.
  3. Both (a) and (b).
  4. Elimination-addition mechanism.
  1. Phenol undergoes electrophilic substitution more readily than benzene because:
  1. The intermediate carbocation is a resonance hybrid of more resonating structures than that from benzene.
  2. The intermediate is more stable as it has positive charge on oxygen, which can be better accommodated than on carbon.
  3. In one of the canonical structures, every atom (except hydrogen) has complete octet.
  4. The — OH group is o, p-directing which like all other o, p - directing group, is activating.
  1. Phenol on treatment with excess of cone. HNO3 gives:
  1. O - nitrophenol.
  2. P - nitrophenol.
  3. O - and p - nitrophenol.
  4. 2, 4, 6 - trinitrophenol.
  1. Phenol is heated with a solution of mixture of KBr and KBrO3. The major product obtained in the above reaction is:
  1. 2 - bromophenol.
  2. 3 - bromophenol.
  3. 4 - bromophenol.
  4. 2, 4, 6 - tribromophenol.
  1. The major product of the following reaction is:

✓

Answer

    1. (d) Elimination-addition mechanism.
    2. (c) In one of the canonical structures, every atom (except hydrogen) has complete octet.

    Explanation:

    1. (d) 2, 4, 6 - trinitrophenol.

    Explanation:

    1. (d) 2, 4, 6 - tribromophenol.

    ​​​​​​​​​​​​​​​​​​​​​Explanation:

    $\text{KBr}_{\text{(aq)}}+\text{KBrO}_{3\text{(aq)}}\rightarrow\text{Br}_{2\text{(aq)}}$

    This bromine reacts with phenol and 2, 4, 6 - tribromophenol.

    1. ​​​​​​​(b)

    ​​​​​​​

    ​​​​​​​​​​​​​​​​​​​​​Explanation:

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A reaction in which rate ofreaction is independent of concentration of the reactants is called zero order reaction. Photochemical combination of hydrogen and chlorine to give hydrogen chloride is an example of zero order reaction. The rate constant of a zero order reaction is equal to the rate of reaction. The half life period of a zero order reaction is directly proportional to initial concentration of the reactant. For a zero order reaction,

$\text{k}=\frac{1}{\text{t}}\left\{[\text{A}]-[\text{A}]\right\}$

In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion: For a zero order reaction, plot of rate vs concentration will be a straight line parallel to concentration axis.

Reason: For a zero order reaction, rate is independent of concentration.

  1. Assertion: Photochemical combination of hydrogen and chlorine to give hydrogen chloride is an example of zero order reaction.

Reason: The rate of reaction depends on the concentration of hydrogen and independent of concentration of chlorine.

  1. Assertion: If in a zero order reaction, the concentration of the reactant is doubled, the half-life period is also doubled.

Reason: For a zero order reaction, the rate of reaction is independent of initial concentration.

  1. Assertion: ln a reaction A → products, the concentration of the reactant is reduced to zero after a finite time.

Reason: The order of reaction is zero.

  1. Assertion: Rate constant of a zero order reaction has same units as the rate of reaction.

Reason: Rate constant of a zero order reaction does not depend on the unit of concentration.

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Read the passage given below and answer the following questions:

Carbohydrates are polyhydroxy aldehydes and ketones and those compounds which on hydrolysis give such compounds are also carbohydrates. The carbohydrates which are not hydrolysed are called monosaccharides. Monosaccharides with aldehydic group are called aldose and those which free ketonic groups are called ketose. Carbohydrates are optically active. Number of optical isomers = 2n

Where n = numberofasymmetric carbons. Carbohydrates are mainlysynthesised by plants during photosynthesis. The monosaccharides give the characteristic reactions of alcohols and carbonyl group (aldehydes and ketones). It has been found that these monosaccharides exist in the form of cyclic structures. In cyctization, the -OH groups (generally C5 or C4 in aldohexoses and C5 or C6 in ketohexoses) combine with the aldehyde or keto group. As a result, cyclic structures of five or six membered rings containing one oxygen atom are formed, e.g., glucose forms a ring structure. Glucose contains one aldehyde group, one IO alcoholic group and four 2° alcoholic groups in its open chain structure.

The following questions are multiple choice questions. Choose the most appropriate answer:

  1. First member of ketos sugar is:
  1. Ketotriose.
  2. Ketotetrose.
  3. Ketopentose.
  4. Ketohexose.
  1. In CH2OHCHOHCHOHCHOHCHOHCHO, the number of optical isomers will be:
  1. 16
  2. 8
  3. 32
  4. 4
  1. Some statements are given below:
  1. Glucose is aldohexose.
  2. Naturally occurring glucose is dextrorotatory.
  3. Glucose contains three chiral centres.
  4. Glucose contains one 1° alcoholic group and four 2° alcoholic groups.

Among the above, correct statements are:

  1. 1 and 2 only
  2. 3 and 4 only
  3. 1, 2 and 4 only
  4. 1, 2, 3 and 4
  1. Two hexoses fonn the same osazone, find the correct statement about these hexoses.
  1. Both of them must be aldoses.
  2. They are epimers at C-3.
  3. The carbon atoms I and 2 in both have the same configuration.
  4. The carbon atoms 3, 4 and 5 in both have the same configuration.
  1. Which of the following reactions of glucose can be explained only by its cyclic structure?
  1. Glucose forms cyanohydrin with HCN.
  2. Glucose reacts with hydroxylamine to form an oxime.
  3. Pentaacetate of glucose does not react with hydroxylamine.
  4. Glucose is oxidised by nitric acid to gluconic acid.
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The concentration of potassium ions inside a biological cell is at least twenty times higher than the outside. The resulting potential difference across the cell is important in several processes such as transmission of nerve impulses and maintaining the ion balance. A simple model for such a concentration cell involving a metal M is,
M(s) | M+(aq.; 0.05 molar) || M+(aq; 1 molar) | M(s)
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. For the above cell,
  1. $\text{E}_\text{cell}<0;\Delta\text{G}>0$
  2. $\text{E}_\text{cell}>0;\Delta\text{G}<0$
  3. $\text{E}_\text{cell}<0;\Delta\text{G}^\circ>0$
  4. $\text{E}_\text{cell}>0;\Delta\text{G}^\circ<0$
  1. If the 0.05 molar solution of M+ is replaced by a 0.0025 molar M+ solution, then the magnitude of the cell potential would be:
  1. 130mV
  2. 185mV
  3. 154mV
  4. 600mV
  1. The value of equilibrium constant for a feasible cell reaction is:
  1. < 1
  2. = 1
  3. > 1
  4. Zero
  1. What is the emf of the cell when the cell reaction attains equilibrium?
  1. 1
  2. 0
  3. > 1
  4. < 1
  1. The potential of an electrode change with change in:
  1. Concentration ofions in solution.
  2. Position of electrodes.
  3. Voltage of the cell.
  4. All of these.
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When the mixture contains the three amine salts (1º, 2º and 3º) along with quaternary salt, it is distilled with KOH solution. The three amines distill, leaving the quaternary salt unchanged in the solution. Then the mixture of amines is separated by fractional distillation, Hinsberg's method and Hoffmann's method.

The following questions are multiple choice questions. Choose the most appropriate answer:

  1. Hinsberg reagent is:
  1. Aliphatic sulphonyl chloride.
  2. Phthalamide.
  3. Aromatic sulphonyl chloride.
  4. Anhydrous ZnCl2 + cone. HCI.
  1. Primary amine with Hinsberg's reagent forms:
  1. N-alkyl benzene sulphonamide soluble in KOH solution.
  2. N-alkyl benzene sulphonamide insoluble in KOH solution.
  3. N, N-alkyl benzene sulphonamide soluble in KOH solution.
  4. N, N-alkyl benzene sulphonamide insoluble in KOH solution.
  1. Secondary amine with Hinsberg's reagent forms:
  1. N-alkyl benzene sulphonamide soluble in KOH solution.
  2. N-alkyl benzene sulphonamide insoluble in KOH solution.
  3. N,N-dialkyl benzene sulphonamide soluble in KOH solution.
  4. N,N-dialkyl benzene sulphonamide insoluble in KOH solution.
  1. To separate amines in a mixture Hoffmann's method is used. The Hoffman n's reagent is:
  1. Benzenesulphonyl chloride.
  2. Diethyl oxalate.
  3. Benzeneisocyanide.
  4. P-toulenesulphonic acid.
  1. 3º amines with Hinsberg's reagent give:
  1. No reaction.
  2. Product which is same as that of 1° amine.
  3. Product which is same as that of 2° amine.
  4. Products which is a quaternary salt.
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Read the passage given below and answer the following questions:
The unique behaviour of Cu, having a positive E° accounts for its inability to liberate H2 from acids. Only oxidising acids (nitric and hot concentrated sulphuric acid) react with Cu, the acids being reduced. The stability of the half-filled (d5) subshell in Mn2+ and the completely filled (d10) configuration in Zn2+ are related to their $\text{E}^\circ\frac{\text{M}^{3+}}{\text{M}^{2+}}$ values. The low value for Sc reflects the stability of Sc3+ which has a noble gas configuration. The comparatively high value for Mn shows that Mn2+(d5) is particularly stable, whereas a comparatively low value for Fe shows the extra stability of Fe3+(d5). The comparatively low value for Vis related to the stability of v2+ (half-filled t2g level).
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. Standard reduction electrode potential of $\frac{\text{Zn}^{2+}}{\text{Zn}}$ is 0.76V. This means
  1. ZnO cannot be reduced to Zn by H2 under standard conditions.
  2. Zn cannot liberate H2 with concentrated acids.
  3. Zn is generally the anode in an electrochemical cell.
  4. Zn is generally the cathode in an electrochemical cell.
  1. $\text{E}^\circ$ values for the couples $\frac{\text{Cr}^{3+}}{\text{Cr}^{2+}}$ and $\frac{\text{Mn}^{3+}}{\text{Mn}^{2+}}$ are -0.41 and +1.51 volts respectively. These values suggest that.
  1. Cr2+ acts as a reducing agent whereas Mn3+ acts as an oxidizing agent.
  2. Cr2+ is more stable th an Cr3+ state.
  3. Mn3+ is more stable than Mn2+.
  4. Cr2+ acts as an oxidizing agent whereas Mn3+ acts as a reducing agent..
  1. The reduction potential values of M, N and O are +2.46, -1.13 and -3.13V respectively. Which of the following order is correct regarding their reducing property?
  1. O > N > M
  2. O > M > N
  3. M > N > O
  4. M > O > N
  1. Which of the following statements are true?
  1. Mn2+ compounds are more stable than Fe2+ towards oxidation to +3 state.
  2. Titanium and copper both in the first series of transition metals exhibits +1 oxidation state most frequently.
  3. Cu+ ion is stable in aqueous solutions.
  4. The $\text{E}^\circ$ value for the $\frac{\text{Mn}^{3+}}{\text{Mn}^{2+}}$ couple is much more positive than that for $\frac{\text{Cr}^{3+}}{\text{Cr}^{2+}}$ or $\frac{\text{Fe}^{3+}}{\text{Fe}^{2+}}.$.
  1. (II) and (III)
  2. (I) and (IV)
  3. (I) and (III)
  4. (II) and (IV)
  1. The stability of $\text{Cu}^{2+}_\text{(aq)}$ rather than $\text{Cu}^{+}_\text{(aq)}$ is due to.
  1. More negative $\Delta_\text{hyd}\text{H}^\circ$ of $\text{Cu}^{2+}_\text{(aq)}.$
  2. Less negative $\Delta_\text{hyd}\text{H}^\circ$ of $\text{Cu}^{2+}_\text{(aq)}.$
  3. More positive $\Delta_\text{hyd}\text{H}^\circ$ of $\text{Cu}^{2+}_\text{(aq)}.$
  4. Less positive $\Delta_\text{hyd}\text{H}^\circ$ of $\text{Cu}^{2+}_\text{(aq)}.$
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Read the passage given below and answer the following questions:

The order of reactivity towards SN1 reaction depends upon the stability of carbocation in the first step. Greater the stability of the carbocation, greater will be its ease of formation from alkyl halide and hence faster will be the rate of the reaction. As we know, 3º carbocation is most stable, therefore, the tert-alkyl that halides will undergo SN1 reaction very fast. For example, it has been observed that the reaction (CH3)3CBr with OH- ion to give 2-methyl-2-propanol is about I million times as fast as the corresponding reaction of the methyl bromide to give methanol.

The primary alkyl halides always react predominantly by SN2 mechanism. On the other hand, the tertiary alkyl halides react predominantly by SN1 mechanism. Secondary alkyl halides may react by either mechanism or by both the mechanisms without much preference depending upon the nature of the nucleophile and solvent.

In these questions (Q. No. i-tv), a statement of assertion followed by a statement of reason is given. Choose tile correct answer out of tile following choices.

  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion: Low concentration of nudeophile favours SN1 mechanism.

Reason: 2º alkyl halides are less reactive than 1º towards SN1 reactions.

  1. Assertion: Polar solvent slows down SN2 reactions.

Reason: CH3-Br is less reactive than CH3Cl.

  1. Assertion: Benzyl bromide when kept in acetone- water it produces benzyl alcohol.

Reason: The reaction follows SN2 mechanism.

  1. Assertion: Rate of hydrolysis of methyl chloride to methanol is higher in DMF than in water.

Reason: Hydrolysis of methyl chloride follows second order kinetics.

  1. Assertion: SN1 reaction is carried out in the presence of a polar protic solvent.

Reason: A polar protic solvent increases the stability of carbocation due to solvation.

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Read the passage given below and answer the following questions:

Transition elements are elements that have partially filled d-orbitals. The configuration of these elements corresponds to (n - 1)d1-10ns1-2. It is important to note that the elements mercury, cadmium and zinc are not considered transition elements because of their electronic configurations, which corresponds to (n - 1)d10ns2. Some general properties of transition elements are:

These elements can fonn coloured compounds and ions due to d-d transition;

These elements exhibit many oxidation states;

A large variety of ligands can bind themselves to these elements, due to this, a wide variety of stable complexes formed by these ions. The boiling and melting point of these elements are high. These elements have a large ratio of charge to the radius.

In these questions (Q. No. i-iv), a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.

  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion: Tungsten has very high melting point.

Reason: Tungsten is a covalent compound.

  1. Assertion: Zn, Cd and Hg are normally not considered transition metals.

Reason: d-Orbitals in Zn, Cd and Hg elements are completely filled, hence these metals do not show the general characteristics properties of the transition elements.

  1. Assertion: Copper metal gets readily corroded in acidic aqueous solution such as HCl and dil. H2SO4.

Reason: Free energy change for this process is positive.

  1. Assertion: Tailing of mercury occurs on passing ozone through it.

Reason: Due to oxidation of mercury.

  1. Assertion: Transition metals are poor reducing agents.

Reason: Transition metals fonn numerous alloys with other metals.

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Read the passage given below and answer the following questions:
A compound (X) containing C, H and O is unreactive towards sodium. It also does not react with Schiff s reagent. On refluxing with an excess of hydroiodic acid, (X) yields only one organic product ( Y). On hydrolysis, (Y) yields a new compound (Z) which can be converted into (Y) by reaction with red phosphorus and iodine. The compound (Z) on oxidation with potassium permanganate gives a carboxylic acid. The equivalent weight of this acid is 60.
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. The compound (X) is an:
  1. Acid.
  2. Aldehyde.
  3. Alcohol.
  4. Ether.
  1. The IUPAC name of the acid formed is:
  1. Methanoic acid.
  2. Ethanoic acid.
  3. Propanoic acid.
  4. Butanoic acid.
  1. Compound (Y) is:
  1. Ethyl iodide.
  2. Methyl iodide.
  3. Propyl iodide.
  4. Mixture of (a) and (b).
  1. Compound (Z) is:
  1. Methanol.
  2. Ethanol.
  3. Propanol.
  4. Butanol.
  1. Compound (X) on treatment with excess of Cl2 in presence of tight gives:
  1. $\propto-$ Chlorodiethyl ether.
  2. $\propto,\propto'-$ Dichlorodiethyl ether.
  3. Perchlorodiethyl ether.
  4. None of these.
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Read the passage given below and answer the following questions:
To explain bonding in coordination compounds various theories were proposed. One of the important theory was valence bond theory. According to that, the central metal ion in the complex makes available a number of empty orbitals for the formation of coordination bonds with suitable ligands. The appropriate atomic orbitals of the metal hybridise to give a set of equivalent orbitals of definite geometry.
The d-orbitals involved in the hybridisation may be either inner d-orbitals i.e., (n - 1)d or outer d-orbitals i.e., nd. For example, Co3+ forms both inner orbital and outer orbital complexes, with ammonia it forms [Co(NH3)6]3+ and with fluorine it forms [CoF6]3- complex ion.
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. Which of the following is not true for [CoF6]3-?
  1. It is paramagnetic.
  2. It has coordination number of 6.
  3. It is outer orbital complex.
  4. It involves d2sp3 hybridisation.
  1. [Cr(H2O)6]Cl3 (at. no. of Cr = 24) has a magnetic moment of 3.83B.M. The correct distribution of 3d-electrons in the central metal of the complex is:
  1. $3\text{d}^1_\text{xy},3\text{d}^1_{\text{x}^2-\text{y}^2},3\text{d}^1_\text{yz}$
  2. $3\text{d}^1_\text{xy},3\text{d}^1_{\text{yz}},3\text{d}^1_\text{zx}$
  3. $3\text{d}^1_\text{xy},3\text{d}^1_{\text{zy}},3\text{d}^1_{\text{z}^2}$
  4. $3\text{d}^1_{\text{x}^2-\text{y}^2},3\text{d}^1_{\text{z}^2},3\text{d}^1_\text{xz}$
  1. Which of the following is true for [Co(NH3)6]3+?
  1. It is an octahedral, di magnetic and outer orbital complex.
  2. It is an octahedral, paramagnetic and outer orbital complex.
  3. It is an octahedral, paramagnetic and inner orbital complex.
  4. It is an octahedral, di magnetic and inner orbital complex.
  1. The paramagnetism of [CoF6]3- is due to.
  1. 3 electrons.
  2. 4 electrons.
  3. 2 electrons.
  4. 1 electron.
  1. Which of the following is an inner orbital or low spin complex?
  1. [Ni(H2O)6]3+
  2. [FeF6]3-
  3. [Co(CN)6]3-
  4. [NiCl4]2-
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Read the passage given below and answer the following questions:

The phenomenon of the flow of solvent through a semipermeable membrane from pure solvent to the solution is called osmosis.

Sometimes a pressure is applied to stop the process of osmosis, this is known as osmotic pressure. It is denoted by $\pi.$ Osmotic pressure is expressed as : $\pi=\text{CRT}$

Since, osmotic pressure depends upon the molar concentration of solution, therefore it is a colligative property.

A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion: If red blood cells were removed from the body and placed in pure water, pressure inside the cells increases.

Reason: The concentration of salt content in the cells increases.

  1. Assertion: The osmotic pressure of a solution obtained by mixing 100mL of 3.4% solution of urea and 100mL of 1.6% solution of cane sugar at 293K is 7.46 bar.

Reason: The total osmotic pressure will be equal to the sum of partial osmotic pressures.

  1. Assertion: When a solution is separated from the pure solvent by a semipermeable 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 to a region of low concentration solution.

  1. Assertion: Two solutions having same osmotic pressure at a given temperature are called isotonic solutions.

Reason: Osmotic pressure is not a colligative property.

  1. Assertion: The preservation of meat by salting and fruits by adding sugar protects against bacterial action.

Reason: A bacterium on salted meat or candid fruit loses water due to osmosis shrivels and ultimately dies.

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