Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Ease of nucleophilic addition in the given compounds is

  • I > III > II

  • II > III > I

  • II > I > III

  • III > I > II


B.

II > III > I

Aromatic aldehydes and ketones are less reactive than the corresponding aliphatic analogues towards nucleophilic addition reactions due to the +R effect of benzene ring. Further, aldehydes are more reactive than ketones due to +I effect and steric effect of alkyl group. Therefore, the ease of nucleophilic addition will follow the order


12.

Assertion : A reaction which is spontaneous and accompanied by decrease of randomness must be exothermic.

Reason : All exothermic reactions are accompanied by decrease of randomness.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

G=H-TS

As the reaction is accompained by decrease in randomness,

G=H+TSSisnegative

For reaction to be spontaneousGshould be negative which is possible only if reaction is highly exothermic,i.e.His negative.

Exothermic reactions may be accompained by increase or decrease of randomness.


13.

Assertion : For hydrogen like species, energy of an electron in a particular orbit increases with increase in value of Z.

Reason : Electronegativity decreases across a period.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false


C.

If assertion is true but reason is false.

For hydrogen like species, energy of an electron in nth orbit is given by

En = -2π2mZ2e4k2n2h2(EnZ2)

Electronegativity increases across a period with decrease in size of atoms.


14.

For which of the following elements it is difficult to disproportionate in +3 oxidation state ?

  • N

  • As

  • Sb

  • Bi


D.

Bi

In nitrogen family, due to inert pair effect as the tendency to show +3 oxidation state increases down the group from As to Bi, tendency to disproportionate decreases.


15.

Assertion : C- O....- H bond angle is less than the normal tetrahedral bond angle.

Reason : Lone pair-lone pair repulsion decreases bond angle.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

The C -O....- Hbond angle in alcohols is slightly less than the tetrahedral angle 109°28' due to repulsion between the unshared electron pairs of oxygen.


16.

Assertion : Heat of neutralisation for both H2SO4 and HCl with NaOH is 53.7 kJ mol-1.

Reason : Both HCl and H2SO4 are strong acids.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

Because HCl and H2SO4are strong acids, their heat of neutralisation is 53.7 kJ mol-1.


17.

Assertion : H2S is stronger acid than PH3.

Reason : S is more electronegative than P, conjugate base HS- is more stable than H2P-.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

H2S(g) + aq HS- (aq) + H+ (aq)

PH3 (g) + aq H2P- + H+ (aq)

AsS is more electronegative than P, conjugate base HS- is more stable than H2P-.Hence, H2S is stronger acid than PH3.


18.

Assertion : Diamagnetic substances are not attracted by magnetic field.

Reason : Diamagnetic substances have no unpaired electrons.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

Due to absence of unpaired electrons in dimagnetic substances, they are not attracted by magnetic field.


19.

Assertion : Critical temperature of CO2 is 304 K, it cannot be liquified above 304 K.

Reason : At a certain temperature, volume1pressure

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


B.

If both assertion and reason are true but reason is not the correct explanation of assertion

Critical temperature of a gas is defined as the temperature above which it cannot be liqufied. However, high pressure may be applied on the gas. Hence, CO2 cannot be liquified above its critical temperature.

According to Boyle's law,

P1VorV1P( at constant T and n)


20.

Assertion : Generally alkali and alkaline earth metals form superoxides.

Reason: There is a single bond between O and O in superoxides.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


D.

If both assertion and reason are false

Only K, Rb and Cs from alkali metals form superoxides and superoxides possess three electron bond (:O..-...O..:)-.