Tag: p- block elements-ii

Questions Related to p- block elements-ii

The single $X-X$ bond made by $N$ is weaker than that of $P$ because:

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

  1. of repulsion between nitrogen nucleus due to smaller size of nitrogen atom

  2. of repulsion between non-bonded electrons due to smaller size of nitrogen atom

  3. of higher bond enthalpy of nitrogen

  4. all of the above

Show answer
Correct Option: B
Explanation:

The single $N-N$ bonds formed is weaker than single $P-P$ bonds because of lone pair repulsion on small nitrogen molecule.

Which of the following does not contain nitrogen?

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

  1. Proteins in plants and animals

  2. Members of apatite family

  3. Indian saltpetre

  4. Chile saltpetre

Show answer
Correct Option: B
Explanation:

Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite and chlorapatite, with high concentrations of $OH^{-},F{-},Cl{-}$ respectively, in the crystal. Proteins in plants and animals have nitrogen. Chile saltpetre and Indian saltpetre are $NaNO _3$ and $KNO _3$ respectively.

Which of the following gives purest form of nitrogen?

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

  1. Thermal decomposition of ammonium nitrate

  2. Treating aqueous solution of ammonium chloride with sodium nitrite

  3. Thermal decomposition of sodium or barium azide

  4. Liquefaction and fractional distillation of air

Show answer
Correct Option: C
Explanation:

$2NaN _3 \rightarrow 2Na +3N _2$ 

Pure nitrogen can be obtained from thermal decomposition of sodium or barium azide.

Nitrogen can exhibit which of the following oxidation states:

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

  1. $+1$

  2. $+2$

  3. $+3$

  4. all of the above

Show answer
Correct Option: D
Explanation:

Nitrogen forms oxides in which nitrogen exhibits each of its positive oxidation numbers from +1 to +5. $N _2O$ has nitrogen in the +1 oxidation state, $NO$ has +2 and $NO _2$ has +4 oxidation state.

Nitrogen and phosphorus are both in Group 15 of the Periodic Table. Phosphorus forms a chloride with the formula $P{Cl} _{5}$ but nitrogen does not form $N{Cl} _{5}$.
Which statements help to explain this?
1. Nitrogen's outer shell cannot contain more than eight electrons.
2. Nitrogen cannot have an oxidation state of $+5$
3. Nitrogen is less electronegative than phosphorus.

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

  1. 1, 2 and 3 are correct

  2. 1 and 2 only are correct

  3. 2 and 3 only are correct

  4. 1 only is correct

Show answer
Correct Option: D
Explanation:

Only highly electrnegative elements can make nitrogen exhibit +5 oxidation state


We know that, on going from top to bottom in a group, non- metalllic character decreases. The non- metallic character of any element is characterized by its tendency to lose electron i.e electronegativity.
Hence, electronegativity decreases on going from top to bottom in a group.
Therefore, Nitrogen is more electronegative than Phosphorus.

Also, Nitrogen is smaller in size as compared to Phosphorus. Due to its small size, the net electron charge increases. Hence, its nucleus exerts greater force on the electrons.
Thetefore, its tendency to gain electron is more as compared to that of Phosphorus.
That is the reason why, Nitrogen is more electronegative element than Phosphorus.


How many oxides of monomeric nature can nitrogen form?

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

  1. $1$

  2. $2$

  3. $4$

  4. $5$

Show answer
Correct Option: A
Explanation:

$N$ has 5 valence electron, therefore molecules with $N _2O _x$ will have even number of electrons and will be non radical. For monomeric oxide, $N _2O$ is the only monomeric nitrogen oxide.

Therefore option A is correct.

Select the correct statement for brown ring test.

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

  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.

Show answer
Correct Option: A,B,C,D
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.

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

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

  1. $NO^- _3$

  2. $SO^{-2} _3$

  3. $BO^{-3} _3$

  4. $CO^{-2} _3$

Show answer
Correct Option: B
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.

Which of the following elements occur free in nature?

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

  1. Nitrogen

  2. Phosphorus

  3. Arsenic

  4. Antimony

Show answer
Correct Option: A
Explanation:

The nitrogen which exists free in nature which is made up of 78% of Earth atmosphere and naturally found in mineral deposits, soil and organic compounds.

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

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

  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 $P$

Show answer
Correct Option: B,D
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.