Tag: nitrogen - 15 group

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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.

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

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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

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

Which of the following does not contain nitrogen?

  1. Proteins in plants and animals

  2. Members of apatite family

  3. Indian saltpetre

  4. Chile saltpetre
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Which of the following gives purest form of nitrogen?

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$2NaN _3 \rightarrow 2Na +3N _2$ 

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

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

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.

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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.