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Which of the following statements is not correct for a nucleophile?

  • Option 1)

    Nucleophile is a Lewis acid

  • Option 2)

    Ammonia is a nucleophile

  • Option 3)

    Nucleophiles attack on less e- density sites

  • Option 4)

    Nucleophiles are not electron seeking

 

As we learnt in

Nucleophile -

Those e- rich  chemical species having capacity to attack e-deficient portion of substrate.

- wherein

Nucleophile must have complete octet and atleast one lone pair

 

 Nucleophiles are those compounds which has a lone pair of electron . Lewis acid has deficiency of electron. Hence a nucleophile can't be a Lewis acid. 

 


Option 1)

Nucleophile is a Lewis acid

Correct

Option 2)

Ammonia is a nucleophile

Incorrect

Option 3)

Nucleophiles attack on less e- density sites

Incorrect

Option 4)

Nucleophiles are not electron seeking

Incorrect

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Posted by

subam

The number of structural isomers possible from the molecular formula C3H9N is:

  • Option 1)

    4

  • Option 2)

    5

  • Option 3)

    2

  • Option 4)

    3

 

As we learnt in

Isomerism in nitro compounds -

Nitroalkanes shows chain, position, functional isomerism and Tautomerism.

-

 

 

 


Option 1)

4

Correct

Option 2)

5

Incorrect

Option 3)

2

Incorrect

Option 4)

3

Incorrect

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Posted by

Aadil

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An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron What will be the direction of current if any, induced in the coil?

  • Option 1)

    adcb

  • Option 2)

    The current will reverse its direction as the electron goes past the coil

  • Option 3)

    No current induced

  • Option 4)

    abcd

 

 

Faraday’s First Law -

Whenever the number of magnetic lines of force (Magnetic Flux) passing through a circuit changes an emf called induced emf is produced in the circuit.   

-

 

 Initially electron is approaching the coil and then its leaving the coil. Hence first flux will increase and then decrease. Direction as electron goes past the coil.


Option 1)

adcb

This is incorrect option

Option 2)

The current will reverse its direction as the electron goes past the coil

This is  correct option

Option 3)

No current induced

This is incorrect option

Option 4)

abcd

This is incorrect option

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Posted by

Vakul

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

  • Option 1)

    -CH2Cl

  • Option 2)

    -COOH

  • Option 3)

    -CHCl2

  • Option 4)

    -CHO

 

 

Reimer Tiemann's reaction -

The electrophile used is CCl2  (Dichloromethylene) -CHO is introduced in the ortho position.

- wherein

 

 


Option 1)

-CH2Cl

This option is incorrect 

Option 2)

-COOH

This option is incorrect 

Option 3)

-CHCl2

This option is incorrect 

Option 4)

-CHO

This option is correct 

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Posted by

Aadil

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

(I)       CH_{3}CH_{2}OH+HCl\overset{anh.ZnCl_{2}}{\rightarrow}

(II)       CH_{3}CH_{2}OH+HCl \rightarrow

(III)       (CH_{3})_{3}COH+HCl \rightarrow

(IV)       (CH_{3})_{2}CHOH+HCl \overset{anh.ZnCl_{2}}{\rightarrow}

  • Option 1)

    (I), (III) and (IV) only

  • Option 2)

    (I) and (II) only

  • Option 3)

    (IV) only

  • Option 4)

    (III) and (IV) only

 

As we learnt in 

Alcohols reaction with hydrogen halides -

Forms alkyl halides.

- wherein

ROH+HX\rightarrow RX+H_{2}O

 

 Tertiary alcohols forms alkyl halides but not easily due to the higher stability of tertiary carbocation 


Option 1)

(I), (III) and (IV) only

This solution is correct 

Option 2)

(I) and (II) only

This solution is incorrect 

Option 3)

(IV) only

This solution is incorrect 

Option 4)

(III) and (IV) only

This solution is incorrect 

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Posted by

Plabita

Which of the following statements is not correct for a nucleophile ?

  • Option 1)

    Nucleophile is a Lewis acid

  • Option 2)

    Ammonia is a nucleophile

  • Option 3)

    Nucleophiles attack low e- density sites

  • Option 4)

    Nucleophiles are not electron seeking

 

As we learnt in

Nucleophile -

Those e- rich  chemical species having capacity to attack e-deficient portion of substrate.

- wherein

Nucleophile must have complete octet and atleast one lone pair

 

 Nucleophiles are those having capacity to donate electrons s.e they, Lewis base

 

 


Option 1)

Nucleophile is a Lewis acid

This option is correct.

Option 2)

Ammonia is a nucleophile

This option is incorrect.

Option 3)

Nucleophiles attack low e- density sites

This option is incorrect.

Option 4)

Nucleophiles are not electron seeking

This option is incorrect.

View Full Answer(1)
Posted by

Plabita

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Method by which Aniline cannot be prepared is :

  • Option 1)

    hydrolysis of phenylisocyanide with acidic solution.

  • Option 2)

    degradation of benzamide with bromine in alkaline solution.on.

  • Option 3)

    reduction of nitrobenzene with H2/Pd in ethanol.

  • Option 4)

    potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution.

 

As we learnt in

Gabriel Phthalimide Synthesis -

Further alkylation can be stopped and a pure primary amine can be obtained by alkylation of phthalimide ( Gabriel synthesis ) followed by hydrolysis.

- wherein

 

 Gabrief Alkalimide synthesis of primary amines. 

Because there exist partial double between chlorine and carbon.

 


Option 1)

hydrolysis of phenylisocyanide with acidic solution.

Incorrect

Option 2)

degradation of benzamide with bromine in alkaline solution.on.

Incorrect

Option 3)

reduction of nitrobenzene with H2/Pd in ethanol.

Incorrect

Option 4)

potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution.

Correct

View Full Answer(1)
Posted by

Plabita

A gas such as carbon monoxide would be most likely to obey the ideal gas law at:

  • Option 1)

    high temperatures and low pressures.

  • Option 2)

    low temperatures and high pressures.

  • Option 3)

    high temperatures and high pressures.

  • Option 4)

    low temperatures and low pressures.

 

As we learned in concept no

Kinetic Theory of Gases -

Molecules of gases are very small and their actual volume is negligible in comparision to the empty space between them.

-

 

 Ideal gas behaviour is based on the following assumption

molecules of gases are very small and their actual volume is negligible in comparision to the empty space between them

There is no force of attraction between the particle of a gas at ordinary temperature and pressure

These assumptions are only valid at high temperatures and low pressures


Option 1)

high temperatures and low pressures.

This option is correct

Option 2)

low temperatures and high pressures.

This option is incorrect

Option 3)

high temperatures and high pressures.

This option is incorrect

Option 4)

low temperatures and low pressures.

This option is incorrect

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Posted by

Vakul

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Point masses m1 and m2 are placed at the opposite ends of a rigid rod of length L, and negligible mass. The rod is to be set rotating about an axis perpendicular to it. The position of point P on this rod through which the axis should pass so that the work required to set the rod rotating with angular velocity \omega _0 is minimum, is given by :

  • Option 1)

    x = \frac{{\text{m}_1 }} {{\text{m}_2 }}\text{L}

  • Option 2)

    x = \frac{{\text{m}_2 }} {{\text{m}_1 }}\text{L}

  • Option 3)

    x = \frac{{\text{m}_2 \text{L}}} {{\text{m}_1 + \text{m}_2 }}

  • Option 4)

    x = \frac{{\text{m}_1 \text{L}}} {{\text{m}_1 + \text{m}_2 }}

 

As we learned in concept

Moment of inertia for system of particle -

I= m_{1}r_{1}^{2}+m_{2}r_{2}^{2}+.........m_{n}r_{n}^{2}

dpi{100} = sum_{i=1}^{n}: m_{i}r_{i}^{2}

 

- wherein

Applied when masses are placed discretely.

 

 Total M.I of rod

I = m_{1}x^{2}+m_{2}(L-x)^{2}

I = m_{1}x^{2}+m_{2}L^{2}+m_{2}x^{2}-m_{2}Lx

As I is minimum i.e.

\frac{di}{dx} = 2m_{1}x+0+2xm_{2}-2m_{2}L=0

=>x(2m_{1}+2m_{2})= 2m_{2}L

x = \frac{m_{2}L}{m_{1}+m_{2}}


Option 1)

x = \frac{{\text{m}_1 }} {{\text{m}_2 }}\text{L}

this is the incorrect option

Option 2)

x = \frac{{\text{m}_2 }} {{\text{m}_1 }}\text{L}

this is the incorrect option

Option 3)

x = \frac{{\text{m}_2 \text{L}}} {{\text{m}_1 + \text{m}_2 }}

this is the correct option

Option 4)

x = \frac{{\text{m}_1 \text{L}}} {{\text{m}_1 + \text{m}_2 }}

this is the incorrect option

View Full Answer(1)
Posted by

Plabita

An automobile moves on a road with a speed of 54 km h-1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is :

  • Option 1)

    8.58 kg m2 s-2

  • Option 2)

    10.86 kg m2 s-2

  • Option 3)

    2.86 kg m2 s-2

  • Option 4)

    6.66 kg m2 s-2

 

As we learned in concept

Analogue of second law of motion for pure rotation -

vec{	au }=I, alpha

- wherein

Torque equation can be applied only about two point

(i) centre of motion.

(ii) point which has zero velocity/acceleration.

 

 V=54 Km/hr = 15m/s

 

Angular velocity of vehicle V=W0r

W_{0} = \frac{V}{R} = \frac{15}{0.45} = \frac{100}{3} rad/s

Angular Accn          \propto = \frac{\Delta W}{t} = \frac{-100}{45} \:rad/s^{2}

\vec{\tau }=I\propto

=> 3\times\frac{100}{45}=6.66\:Kg\:m^{2}s^{-2}

 

 


Option 1)

8.58 kg m2 s-2

This option is incorrect.

Option 2)

10.86 kg m2 s-2

This option is incorrect.

Option 3)

2.86 kg m2 s-2

This option is incorrect.

Option 4)

6.66 kg m2 s-2

This option is correct.

View Full Answer(1)
Posted by

prateek

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