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

Which of the following statements is correct ?

  1. In trisilylamine $p\pi - d\pi $ back bonding takes place.
  2. These are two $p\pi - d\pi $ bonds in molecule.

  3. Fraction of s-character in hybride around the central atom in molecule is 0.5
  4. ${\left( {{\text{C}}{{\text{H}} _{\text{3}}}} \right) _{\text{3}}}{\text{COH}}$ is more acidic than ${\left( {{\text{C}}{{\text{H}} _{\text{3}}}} \right) _{\text{3}}}{\text{SiOH}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In trisilylamine N(SiH3)3, the nitrogen uses its lone pair to form pπ-dπ back bonds with empty d-orbitals of silicon. This is similar to back bonding in trimethylamine N-oxide. Option B is incorrect (no count given), Option C's hybrid claim is questionable, and Option D is wrong - silanols are more acidic than alcohols.

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

Nitrogen differs from P, As, Sb and Bi in the following properties :

  1. It forms diatomic molecule.

  2. It is not able to extent its coordination number beyond four.

  3. Nitrogen does not function as a Lewis acid whereas P, As, Sb and Bi do so.

  4. In all the properties given above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

As vacant d-orbital are present in P and other elements of this group except N so they can expand their valency and forms stable pentavalence product but due to absence of d-orbitals nitrogen cannot form pentavalence products.

It forms diatomic molecule $N _2$.
Nitrogen does not function as a Lewis acid due to absence of d-orbitals and it is a Lewis base due to presence of lone pair.

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

The anomalous behaviour of nitrogen is due to:

  1. small size and high electronegativity

  2. non availability of d-orbitals in valency shell

  3. ease of multiple bond formation

  4. all are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nitrogen differs from other members of the group due to its smaller size, high electronegativity, high IE and non availability of d-orbitals. Nitrogen has unique ability to form $p\pi - p\pi $ multiple bonds with itself and with other elements having small size and high electronegativity.

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

An element X combines with hydrogen to form a compound $XH _3$. The element X is placed on the right side ofthe periodic table. What is true about the element X?
A. Has 3 valence electrons.
B. Is a metal and is solid.
C. Is a non-metal and is a gas.
D. Has 5 valence electrons.
E. $XH _3$  reacts with water to form a basic compound?

  1. A, B and C

  2. B,C and D

  3. C, D and E

  4. E, A and B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Here, $X$ is nitrogen with atomic number 7 and electronic configuration $ { 1s }^{ 2 }{ 2s }^{ 2 }{ 2p }^{ 3 } $ 

It is a non metal belonging to group 15.
Solution of ammonia In water is alkaline in nature and is highly soluble in water.

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

Identify the true statement regarding nitrates of all metals.

  1. All nitrates decompose to give $N{ O } _{ 2 }$

  2. All nitrates are soluble in water

  3. All nitrates are insoluble in water

  4. All nitrates are stable to heat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nitrates of divalent and trivalent metals (Mg, Ca, Ba, Pb, Cu, Zn, Hg, Al, Fe etc.) decompose on heating to give reddish brown fumes of nitrogen dioxide.

The nitrates, chlorates, and acetates of all metals are soluble in water.

Nitrates are not stable to heat they decompose to release nitrogen dioxide.


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

Which molecule is relatively more stable?

  1. $O _2$
  2. $H _2$
  3. $Li _2$
  4. $N _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nitrogen molecule ($\displaystyle N _2$) is relatively more stable. Each $N$ atom has completed its octet and there is a triple bond between two $N$ atoms. In other molecules, there is either a single bond or a double bond between two atoms. A triple bond is stronger than a single or double bond.

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

The impurities formed during laboratory preparation of dinitrogen from ammonium chloride and sodium nitride is/are:

  1. $HCl$
  2. $HNO _3 and NO $
  3. $NO _2$
  4. $HNO _2$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

$NH _4Cl+NaNO _2 \rightarrow N _2+NaCl+2H _2O$

The impurities formed are small amount of $NO$ and $HNO _3$ , which can be removed by passing gas through aqueous sulphuric acid containing potassium dichromate.