Tag: anomalous properties of nitrogen

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Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Select the correct statement for brown ring test.

  1. Nitrates are converted to $NO$
  2. $NO$ forms complex with $Fe$
  3. $Fe^{2+}$ acts as reducing agent here.

  4. Brown colour is due to the complex formation.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation
$ 2HNO _3+ 3H _2SO _4 + 6FeSO _4 \rightarrow 3Fe _2(SO _4) _3 + 2NO + 4H _2O $ $[Fe(H _2O) _6]SO _4+NO \rightarrow [Fe(H _2O) _5(NO)]SO _4+H _2O$ Nitrates are converted into nitric oxide. $NO$ forms complex with $Fe$. $Fe^{2+}$ acts as reducing agent. $[Fe(H _2O) _5(NO)]SO _4$ is brown coloured complex formed.
Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Which of the following do have $p _{\pi}$ - $d _{\pi}$ bonding?

  1. $NO^- _3$
  2. $SO^{-2} _3$
  3. $BO^{-3} _3$
  4. $CO^{-2} _3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$p\pi-d\pi$ bonding includes d-orbitals,if you observe the options only S belongs to $3^{rd}$ period and has d-orbitals(though unoccupied in ground state).

Other options $C$ and $N$ belongs to $2^{nd}$ period while B belongs to $1^{st}$ period and doesn't have d-orbitals.

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Single $N-N$ bond is weaker than the single $P-P$ bond. This is because of:

  1. larger $N-N$ bond length in comparison to $P-P$ bond length
  2. high interelectronic repulsion of the non-bonding electrons, owing to the small $N-N$ bond length in comparison to that in $P-P$ single bond
  3. higher electronegativity of $N$ in comparison to $P$
  4. smaller atomic size of $N$ as compared to that of $P$
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

$N-N$ single bond is weaker than $P-P$ bond due to smaller size of $N$ as compared to $P$. Smaller size of $N$ leads to smaller $N-N$ bond length. As a result, the lone pair of electrons on the both the $N$ atoms repel each other leading to unstability or weakening of $N-N$ bond. Because of larger size of $P$ atom, $P-P$ bond length is more and lone pair-lone pair repulsion between $P$ atoms is less which makes the $P-P$ bond stronger than $N-N$ bond.

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Alkali metals dissolve in liquid ammonia and produces _______.

  1. deep blue solution

  2. a solution which are conducting in nature

  3. red coloured solution
  4. Both $1$ and $2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alkali metal when reacts with liquid ammonia reaction is given by,


$ M +(x+y) NH _3\rightarrow M^+(NH _3)x + e^{-}(NH _3) _y$

 this electrons is free and gives very good conductivity as well blue colour.

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

$N _{2}H _{4}+2H _{2}O _{4}\rightarrow 4H _{2}O _2$. 


This equation suggests the use of $H _{2}O _{2}$ as :

  1. Bleaching agent

  2. Antisepics

  3. Restoring colour of old paintings

  4. Rocket Propellant
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hydrazine (N2H4) reacts with hydrogen peroxide as a rocket propellant, producing energy and gases for thrust. The equation suggests an oxidation reaction where H2O2 acts as an oxidizer. H2O2 is not used as bleaching agent, antiseptic, or for restoring paintings in this context.

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

$CN^-$ and $N _2$ are isoelectronic. But in contrast to $CN^-, N _2$ is chemically inert because of:

  1. smaller $N-N$ bond energy
  2. larger $N-N$ bond energy

  3. low inoziation enthalpy

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both $CN^-$ and $N _2$ have the same number of electrons but $N _2$ is more stable and chemically inert. This is because $N _2$ has a very high bond energy because of the presence of a triple bond between the two $N$ atoms. Both atoms in $N _2$ have achieved a stable electronic configuration, making the $N _2$ atom highly stable. $CN^-$ also has a triple bond but the bond is polar, unlike $N _2$ in which there is no bond polarity. Therefore, $CN^-$ is less stable and not chemically inert.