Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

The intermediate J in the following Wittig reaction is


A.

The intermediate J in the above given Wittig reaction is-


52.

Cupric compounds are more stable than their cuprous counterparts in solid state. This is because

  • the endothermic character of the 2nd IP of Cu is not so high

  • size of Cu2+ is less than Cu+

  • Cu2+ has stable electronic configuration as compared to Cu+

  • the lattice energy released for cupric compounds is much higher than Cu+


A.

the endothermic character of the 2nd IP of Cu is not so high

B.

size of Cu2+ is less than Cu+

D.

the lattice energy released for cupric compounds is much higher than Cu+

Electronic configuration of cuprous (Cu+) and cupric (Cu2+) ions are as follows-

Cu+ = [Ar] 3d104s0

Cu2+ = [Ar] 3d94s0

Electronic configuration of Cu+ is more stable as compared to Cu2+. It is because in Cu2+(small size) the nuclear charge is sufficient to hold 27 electrons whereas in Cu+ such condition is not possible.

Further, the IInd IP of Cu is not very high as compared to its Ist IP. Consequently a large amount of lattice energy is released for cupric compounds as compared to Cu+  compounds.


53.

The number of amino acids and number of peptide bonds in a linear tetrapeptide (made of different amino acids) are respectively

  • 4 and 4

  • 5 and 5

  • 5 and 4

  • 4 and 3


D.

4 and 3

Combination of four amino acid units gives a linear tetrapeptide, in which three peptide bonds are present.


54.

An amine C3H9N reacts with benzene sulphonyl chloride to form a white precipitate which is insoluble in aq. NaOH. The amine is


B.

Since, the amine gives white precipitate with benzene sulphonyl chloride which is insoluble in aq. NaOH, so it must be a secondary amine (i.e., amine having RNHR group).

Among the given compounds, only option 2 is correct. It is a secondary amine, so it represents the structure of given amine.


55.

When phenol is treated with D2SO4 /D2O, some of the hydrogens get exchanged. The final product in this exchange reaction is


A.

In acidic medium, phenol exists in following resonating structures.

Since, o/p positions are electron rich sites, so electrophile will attack on these site, i.e.,
hydrogen of these sites get exchanged by D (deuterium).

Hence, the final product of the reaction is 

It is formed as -


56.

The correct statement regarding the following compounds is

  • all three compounds are chiral

  • only I and II are chiral

  • I and III are diastereomers

  • only I and III are chiral


D.

only I and III are chiral

Here, the image has 2-R, 3-R configuration. Hence, it is a chiral compound.

Here, the image has 2-R, 3-S configuration, i.e. it has plane of symmetry or in other words, rotation of half part is cancelled by the other half. Hence, it is not a chiral compound.

Here, the image has 2-S, 3-S configuration. Hence, it is also a chiral compound.


57.

The reaction of aniline with chloroform under alkaline conditions leads to the formation of 

  • phenylcyanide

  • phenylisonitrile

  • phenylcyanate

  • phenylisocyanate


B.

phenylisonitrile

Aniline is a primary amine that consists of -NH2 group. When it is treated with chloroform under alkaline conditions, it results in the formation of a bad smelling compound, known by the name isonitrile or carbylamine. Hence, the reaction is known as carbylamine reaction.


58.

Among the following compounds, the one(s) that gives (give) effervescence with aqueous NaHCO3 solution is (are)

(CH3CO)2 I CH3COOHII  PhOHIII  CH3COCHOIV

  • I and II

  • I and III

  • Only II

  • I and IV


A.

I and II

Only carboxylic acids and their derivatives such as anhydride are capable to give effervescence with aqueous NaHCO3 solution, because they are more acidic as compare  to H2CO3 (carbonic acid).

II.  CH3COOH + NaHCO3  → CH3COONa + H2O + CO2

I. (CH3CO)2O + 2NaHCO3 → 2CH3COONa + H2) + CO2


59.

In the following reaction, the product E is


C.

Aldehydes lacking α-H atom, undergo Cannizzaro reaction if treated with concentrated alkali (NaOH), i.e., one mole of the aldehyde is reduced to alcohol and other mole is oxidised to salt of acid.

Thus, the given aldehyde (glyoxal) undergoes intramolecular Cannizzaro reaction, i.e., its half part is oxidised and half is reduced.


60.

In DNA, the consecutive deoxynucleotides are connected via

  • phosphodiester linkage

  • phosphomonoester linkage

  • phosphotriester linkage

  • amide linkage


A.

phosphodiester linkage

In DNA, the consecutive deoxynucleotides are linked through phosphodiester linkage.