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Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Nitro benzene is:
i) steam volatile 

ii) used as a solvent
iii) Aliphatic compounds 
Iv) lighter than water

  1. (i) and (ii) are correct

  2. (iii) and (iv) are correct

  3. (i) and (iii) are correct

  4. (i) and (iv) are correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitro benzene is steam volatile and is used as solvent. But it is an aromatic compound and is heavier than water. 

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Assertion (A) : Nitro benzene on nitration gives m-dinitro benzene.
Reason (R) : $NO _{2}$ group is meta directing group.

  1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

  2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

  3. Assertion is correct and Reason is wrong.

  4. Assertion is wrong and Reason is correct.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitro benzene on further nitration forms m - dinitro benzene as nitro group is meta directing group. Thus Assertion as well as Reason both are correct and Reason is correct explanation of Asseriton.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

What is obtained when nitrobenzene is treated sequentially with (i) ${ NH } _{ 4 }Cl/Zn$ dust and (ii) ${ H } _{ 2 }{ SO } _{ 4 }/{ Na } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }$ ?

  1. Benzene

  2. Nitrosobenzene

  3. m-Chlorobenzene

  4. p-Chlorobenzene
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When Nitrobenzene first reacts with $NH _4Cl/Zn$ it forms phenyl hydroxylamine.

When this reacts with $H _2SO _4/ Na _2Cr _2O _7$ it gives Nitroso benzene as a product.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Benzene on reaction with conc. $HNO _{3}$ in presence of conc. $H _{2}SO _{4}$ followed by the treatment of $Cl _{2}$ in presence of $FeCl _{3}$, it gives :

  1. $2 - chloro - 1 - nitrobenzene$
  2. $1 - chloro - 3- nitrobenzene$
  3. $3 - chloro - 1- nitrobenzene$
  4. A mixture of $2 - chloro$ and $4 - chloro - 1 - nitrobenzene$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

3-Chloro-1-nitrobenzene
Nitro substituents have positive charge on the atom bonded to ring. So the like charges repel each other at ortho and para position as compared to meta substitution. So meta position is favored at 3 chloro in the ring.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

When nitrobenzene is treated with $Br _{2}$ in presence of $FeBr _{3}$ the major product formed is m - bromonitrobensene. Statement which is related to obtain the m - isomer is:

  1. The electron density of meta carbon is more than that on ortho and para positions
  2. Loss of aromaticity when $Br^{+}$ attacks at the ortho and para positions and not at meta position
  3. Easier loss of $H^{+}$ to regain aromaticity from the meta position than from ortho and para positions

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The exact influence of a given substituent is seen as its interactions with the delocalized positive charge on the benzonium intermediate generated by bonding to the electrophile at each of the three substitution sites. Nitro groups have a positive charge on the atom bonded to the aromatic ring. Like charges of two groups are destabilized by charge repulsion so meta-products predominate as compared to others.