Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

31.

The hybridization involved in complex [Ni(CN)4]2- is (Atomic number of Ni = 28)

  • dsp2

  • sp3

  • d2sp3

  • d2sp3


A.

dsp2

[Ni(CN)4]2-

Let oxidation state of Ni in [Ni(CN)4]2- is x.

x - 4 = - 2

Or
x= 2

Now, Ni2+ = [Ar] 3d8 4so


therefore, CN- is a strong field ligand. Hence, all unpaired electrons are paired up.



therefore, hybridisation of [Ni(CN)4]2- is dsp2
1641 Views

32.

Which of the following reaction (s) can be used for the preparation of alkyl halides?


straight I. space CH subscript 3 CH subscript 2 OH space plus space HCl space rightwards arrow with Anh. ZnCl subscript 2 on top

II. space CH subscript 3 CH subscript 2 OH space plus space HCl space rightwards arrow

III. space left parenthesis CH subscript 3 right parenthesis subscript 3 COH space plus space HCl space rightwards arrow

IV. space left parenthesis CH subscript 3 right parenthesis subscript 2 CHOH space plus space HCl space rightwards arrow with anh. space ZnCl subscript 2 on top

  • I, III and IV

  • I and II

  • Only IV

  • Only IV


A.

I, III and IV

In the equation (I) and (IV) is the presence of Lucas reagent (HCl + anh.ZnCl2) which on reaction alcohols gives alkyl halides. In equation (III alkyl halides is formed due to SN1 reaction.

847 Views

33.

Strong reducing behaviour of H3PO4 is due to

  • the presence of one -OH group and two P-H bonds

  • high electron gain enthalpy of phosphorous 

  • the high oxidation state of phosphorus

  • the high oxidation state of phosphorus


A.

the presence of one -OH group and two P-H bonds

The oxy-acid of phosphorus which contains P- H bond act as a reducing agent or reductant.



In H3PO2 one -OH group and two P-H bonds are present.

1388 Views

34.

Which of the statements given below is incorrect?

  • Cl2O7 is an anhydride of perchloric acid

  • O3molecule is bent

  • ONF is isoelectronic with NO2

  • ONF is isoelectronic with NO2


D.

ONF is isoelectronic with NO2

Cl2O7 is an anhydride of perchloric acid
2 HClO subscript 4 space rightwards arrow from negative straight H subscript 2 straight O to increment of space Cl subscript 2 straight O subscript 7
The Shape of O3 molecule is bent.


c) Number of electrons in ONF = 24
Number of electrons in NO2 = 24
therefore, ONF and NO2 both are isoelectronic.

d) OF2 is a fluoride of oxygen because electronegativity of fluorine is more than that of oxygen 
OF2 = oxygen difluoride

1054 Views

35.

Which of the following is not the product of dehydration of 


B.

When intermediate carbocation is stable, no rearrangement takes place in carbonation,


633 Views

36.

In an SN1 reaction on chiral centres, there is 

  • 100% racemisation

  • inversion more than retention leading to partial racemization

  • 100% retention

  • 100% retention


B.

inversion more than retention leading to partial racemization

In SN1 reaction, there is slight more inversion product than retention product because SN1 reaction depend on shielding effect of the front side of the reacting carbon.

1283 Views

37.

Method by which aniline cannot be prepared is 

  • hydrolysis phenyl isocyanide with the acidic solution

  • degradation of benzamide with bromine in alkaline solution

  • reduction of nitrobenzene with H2/Pd in ethanol

  • reduction of nitrobenzene with H2/Pd in ethanol


D.

reduction of nitrobenzene with H2/Pd in ethanol

Due to resonance in chlorobenzene C- Cl  bond accquires double bond chracter hence, C -Cl bond is inert towards nucleophile (phthalimide ion)

1090 Views

38.

The reaction of phenol with chloroform in the presence of dilute sodium hydroxide finally introduces, which one of the following functional group? 

  • -CH2Cl

  • -COOH

  • -CHCl2

  • -CHCl2


D.

-CHCl2


This is Reimer - Tiemann reaction.
1495 Views

39.

A reaction of a carbonyl compound with one of the following reagents involves nucleophilic addition followed by the elimination of water. The reagents is 

  • a Grignard reagent

  • hydrazine in presence of feebly acidic solution

  • hydrocyanic acid

  • hydrocyanic acid


C.

hydrocyanic acid

Reaction of carbonyl compounds with ammonia derivatives give addition product followed by the elimination reaction. Slightly acidic medium generate a nucleophilic centre for the attack of weak base like ammonia derivatives.

825 Views

40.

Which one of the following esters gets hydrolysed most easily under alkaline conditions?


A.

Electron withdrawing group attach to the benzene ring increases the reactivity towards nucleophilic substitution reaction, Since, -NO2 group is strong electron withdrawing group. Hence, in basic medium ester containing -NO2 group will be hydrolysed most easily.

1129 Views