Alcohols Phenols and Ethers - Online Test

Answer : Option B
Explaination / Solution:

Phenol is more soluble in NaOH than in water is because phenol is slightly more acidic than alcohols. The Ka for phenol in water is 1e-10 which is not very strong. But by mixing with NaOH, it causes the phenol to release the H+ to form sodium phenoxide.

Answer : Option B
Explaination / Solution:

Hydroxy group is more electron donating group than alkoxy because alkoxy have greater number of atoms than that hydroxyl group there electronic density of oxygen of alkoxy group spreads over the whole group and greater the number of atom less will be the electron donating ability.

Answer : Option A
Explaination / Solution:

-OH is given preference over -Cl so numbering is done so that –OH gets the lowest number.

Answer : Option A
Explaination / Solution:

Cyclopentane is nearly inert chemically, they react with halogens in the presence of light through the substitution of one hydrogen atoms. Since the cyclic structure confers a high degree of symmetry on the molecule, only one monochloro cyclopentane is possible.

Answer : Option A
Explaination / Solution:

The nitro-group is an electron-withdrawing group. The presence of this group in the ortho or para position decreases the electron density in the OH bond. As a result, it is easier to lose a proton. Also, the o-nitrophenoxide or p-nitrophenoxide ion formed after the loss of protons is stabilized by resonance. Hence, ortho and para nitrophenols are stronger acids than phenol.

Answer : Option C
Explaination / Solution:

In cases of halogen derivatives of phenols or aniline or benzoic acid etc, it is very helpful to understand that all halogens when attached to benzene ring exerts -I as well as +R effect. In case of Cl, Br and I, the +R effect has almost no effect on reactivity, acidic character or basic character of benzene ring. It is due to very less effective overlapping involving 2p of carbon and 3p or 4p or 5p of halogen. Hence, only -I effect becomes the deciding factor, which is most dominant from ortho-position and least effective from para-position. So m chlorophenol is most acidic.

Answer : Option B
Explaination / Solution:

B will be most acidic because of –M effect of NO_{​​​​​2} . Followed by d, in d –I effect of NO_{​​​​​2} operates only. Then c will come as –I of OCH_{​​​​3} < - I of NO_{​​​​​2}  and least will be e because of +M effect of OCH_{​​​​3} that will decrease the acidity

Answer : Option D
Explaination / Solution:

The reaction of alkyi halide with sodium alkoxide to give ether (alkoxy alkane), is known as Williamsons synthesis. In this reaction an ether (anisole) is prepared by the action of alkyi halide (methyl iodide) on sodium alkoxide (sodium phenate), so it is an example of Williamsons synthesis.

Answer : Option A
Explaination / Solution:

Alkenes can be prepared from alkyl halides by treatment with alcoholic solution of caustic potash (KOH) at about 353-363 K. This reaction is known as dehydrohalogenation of alkyl halides.

Answer : Option C
Explaination / Solution:

Preparation of phenols from haloarenes: Chlorobenzene is an example of haloarenes which is formed by mono substitution of benzene ring. When chlorobenzene is fused with sodium hydroxide at 623K and 320 atm sodium phenoxide is produced. Finally, sodium phenoxide on acidification gives phenols. Preparation of phenols from diazonium salts: When an aromatic primary amine is treated with nitrous (NaNO2 + HCl) acid at 273 – 278 K, diazonium salts are obtained. These diazonium salts are highly reactive in nature. Upon warming with water, these diazonium salts finally hydrolyse to phenols. Phenols can also be obtained from diazonium salts by treating it with dilute acids. Preparation of phenols from benzene sulphonic acid: Benzenesulphonic acid can be obtained from benzene by reacting it with oleum. Benzenesulphonic acid thus formed is treated with molten sodium hydroxide at high temperature which leads to the formation of sodium phenoxide. Finally, sodium phenoxide on acidification gives phenols.