NEET Chemistry Questions: Alcohol, phenol & ether

Pratcice NEET questions from all capters from huge question bank for free. All MCQs are based on NCERT syllabus. To practice from a specific subject and chapter, select a subject below. Login to practice in a structured way with explanations, bookmarks, lists, notes etc. Click here to Login or Sign up for free.

Question bank:

Among the following sets of reactants which one produces anisole?                           





Anisole is produced by the reaction of phenol (C6H5OH) with sodium hydroxide (NaOH) and methyl iodide (CH3I). This is an example of the Williamson ether synthesis, where an alkoxide ion (from phenol and NaOH) reacts with an alkyl halide to form an ether.

Which one is formed when sodium phenoxide is heated with ethyl iodide?              





Sodium phenoxide reacts with ethyl iodide in a nucleophilic substitution reaction to form phenetole (C6H5OC2H5). The phenoxide ion acts as a nucleophile, attacking the ethyl group and displacing the iodide ion.

Identity Z in the sequence of reactions,                                         

CH3CH2CH=CH2 HBr/H2O2YC2H5ONaZ





(a) CH3CH2CH=CH2Anti-Markownikoff's ruleHBr/H2O2

      CH3CH2CH2CH2BrBromo-butane (1°  product)

      CH3CH2CH2CH2BrSN2 reactionC2H5ONaCH3CH2CH2CH2OC2H5  (williamson's synthesis)

Reaction of ethyl formate with excess of CH3MgI followed by hydrolysis gives





Ethyl formate on reaction with excess of CH3MgI, followed by hydrolysis gives a secondary alcohol i.e. isopropyl alcohol.

Lucas reagent is





(a) The equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 is called Lucas reagent. Lucas reagent is used to distinguish between 1°, 2° and 3° alcohols.

The compound which reacts fastest with Lucas reagent is (at room temperature)              





(d) In Lucas test when Lucas reagent is treated with 1° ,2°  and 3°  alcohols, then turbidity appears, if turbidity is appeared immediately, then alcohol is tertiary. 2-methyl propan-2-ol is a tertiary alcohol. Hence, it reacts fastest with Lucas reagent.

The ionisation constant of phenol is higher than that of ethanol because                





The phenoxide ion (C6H5O-) is stabilized by delocalization of the negative charge over the aromatic ring, making it more stable than the ethoxide ion (CH3CH2O-). This increased stability results in a higher ionization constant for phenol.

The general molecular formula, which represents the homologous series of alkanols is      





(d) Alkanols are the derivates of alkanes which are derived by the replacement of -H of alkanes with -Oh (hydroxyl groups).

       CnH2n+2 →+OH-HCnH2n+1OH or CnH2n+2O

       Alkanes

R-COOHRCH2OH. This reduction cannot be done  by:





 

 

weaker R.A

What mass of isobutylene is obtained from 37 g of tertiary butyl alcohol by heating with 20% H2SO4 at 363 K, if the yield is 65%?





   CH33COH  H2SO4 (CH3)2C=CH2  Molar mass 74             Molar mass 56

      % yield =65

      Real yield = (56/74)x37x(65/100)=18.2 g

How many isomers of C5H11OH will be primary alcohols?





 

 This primary alcohols isomers of C5H11OH are 

(i)

CH3CH2CH2CH2CH2-OH

 

(ii)

CH3-CH|CH3-CH2-CH2-OH

 

(iii)

CH3-CH2-CH|CH3-CH2-OH

 

(iv)

 CH3-C||CH3CH3-CH2-OH

Phenol is less soluble in water. It is due to:





Non-polar part C6H5- shows more hydrophobic nature.

The decreasing order of boiling points of 1°,2°,3° alcohol is:





Branching give rise to decrease in surface area and thus intermolecular forces are lowered.

The boiling points of thio-ethers are .... than those of ether.





(c) Molar mass of thioethers are more than ether.

Which of the following will not form a yellow precipitate on heating with an alkaline solution of iodine?





Methanol (CH3OH) does not contain a hydrogen atom attached to a carbon that is adjacent to an oxygen atom. Therefore, it does not undergo oxidation to form a yellow precipitate when heated with an alkaline solution of iodine.