AP Inter 2nd Year Chemistry Important Questions Chapter 6(d) Group-18 Elements

Students get through AP Inter 2nd Year Chemistry Important Questions Lesson 6(d) Group-18 Elements which are most likely to be asked in the exam.

AP Inter 2nd Year Chemistry Important Questions Lesson 6(d) Group-18 Elements

Very Short Answer Questions

Question 1.
List out the uses of Neon.
Answer:
Uses of Ne:

1. Ne is used in discharge tubes and fluorescent bulbs for advertisement display purpose.
2. ‘Ne’ – bulbs are used in botanical gardens and in green houses.

Question 2.
Write any two uses of argon.
Answer:
Uses of Ar:

1. ‘Ar’ is used to create inert atmosphere in high temperature metallurgical process.
2. ‘Ar’ is used in filling electric bulbs.

Question 3.
In modern diving apparatus, a mixture of He ánd O₂ is used – Why? (IPE 2016 (AP))
Answer:
In modem diving apparatus, a mixture of He and O₂ is used because He is very low soluble in blood.

Question 4.
Helium is heavier than hydrogen. Yet helium is used (instead of H₂) in filling balloons for meteorological observations – Why?
Answer:
‘He’ is a non—inflammable and light gas. Hence it is used in filling balloons for meterological observations.

Question 5.
How is XeO₃ prepared? (IPE May – 2015(AP), 2014)
Answer:
XeF₆ on hydrolysis produce XeO₃.
XeF₆ + 3H₂O → XeO₃ + 6HF

Question 6.
Give the preparation of
a) XeOF₄ and
b) XeO₂F₂. (TS Mar. 17; IPE 2014)
Answer:
Partial hydrolysis of XeF₆ gives oxy fluorides XeOF₄ and XeO₂F₂
XeF₆ + H₂O → XeOF₄ + 2HF
XeF₆ + 2H₂O → XeO₂F₂ + 4HF

Question 7.
Explain the structure of XeO₃. (TS Mar. 17; IPE 16, 15’ 14 (TS))
Answer:
Structure of XeO₃:

1. Central atom is Xe’.
2. ‘Xe undergoes sp³ hybridisation in 3^rd excited state.
   
3. ‘Xe’ forms 3σ-bonds and 3π-bonds with three oxygens.
4. Shape of molecule is pyramidal with bond angle 103°.
   

Question 8.
Explain the shape of XeF₄ on the basis of VSEPR theory.
Answer:
Shape of XeF₄:

1. Central atom in XeF₄ is
   
2. Xe undergoes sp³d² hybridisation in its 2^nd excited state.
3. Shape of the molecule is squãre planar with bond angle 90° and bond length 1.95A
   
4. Xe – forms four σ-bonds by the overlap of sp³d² – 2p_z(F) orbitals.

Question 9.
Which noble gas is radio active ? How is it formed?
Answer:
Radon (Rn) is radio active noble gas. Radon is obtained as decay product of ₈₆R²²⁶.
₈₆Ra²²⁶ → ₈₆Rn²²² + ₂He⁴

Question 10.
How are XeF₂, XeF₄, XeF₆ prepared? Give equation.
Answer:

Question 11.
Noble gases are inert – explain.
Answer:
Noble gases are chemically inert:

1. Noble gases have stable electronic configuration octet configuration except He.
2. Noble gases have high Ionisation energy values and have large positive values of electron gain enthalpy.

Question 12.
Write the name and formula of the first noble gas compound prepared by Bertlett.
Answer:
The first noble gas compound prepared by Bertlett is XePtF₆. Name of the compound is xenon hexa fluoro platinate.

Question 13.
Why do noble gases form compounds with fluorine and oxygen only?
Answer:
Noble gases form compounds with flourine and oxygen only.
Reason: Oxygen and Fluorine are most electronegative elements.

Short Answer Questions

Question 1.
Explain the structures of
a) XeF₂ and
b) XeF₄. (AP Mar. ‘17, IPE 16, 15, ‘14 (TS)) (TS Mar. ’14)
Answer:
Xenon forms the binary fluorides XeF₂, XeF₄, XeF₆ as follows. These are formed by direct combination of Xe and F₂.

Structure of XeF₂:

1. In XeF₂ central atom is ‘Xe’.
2. ‘Xe’ undergoes sp³d hybridisation in its 1^st excited state.
   
3. Shape of molecule is linear.
4. Xe form two σ-bonds with two fluorines.
   

b) Structure of XeF₄:

1. Central atom in XeF₄ is ‘Xe’.
2. Xe undergoes sp³d² hybridisation in it’s 2^nd excited state.
   
3. Shape of the molecule is square planar with bond angle 90° and bond length 1.95A
   
4. Xe forms four σ-bonds by the overlap of sp³d² – 2p_z (F) orbitals.

Question 2.
Explain the structures of
a) XeF₆ and
b) XeOF₄ (IPE Mar & May – 2015, 14)
Answer:
Structure òf XeF₆ is ‘Xe’.

1. Central atom in XeF₆ is ‘Xe’.
2. Xe undergoes sp³d³ hybridisation in it’s 3^rd excited state.
   
3. Shape of molecule is distorted octahedral.
   

b) Structure of XeOF₄:

1. In XeOF₄ molecule ‘Xe’ undergoes sp³d² hybridisation.
2. Shape of the molecule is square pyramid.
3. There is one Xe-O double bond containing.
   
   pπ = dπ overlapping.
   Partial hydrolysis of XeF₆ gives XeOF₄
   XeF₆ + H₂O → XeOF₄ + 2HF
   XeOF₄ is a colourless volatile liquid. It has a square pyramidal shape.

Question 3.
Explain the structure of
a) XeO₃ and
b) XeO₄ (T.S. Mar. ‘16)
Answer:
a) Structure of XeO₃:

1. Central atom is ‘Xe’
2. ‘Xe’ undergoes sp³ hybridisation in 3^rd excited state.
   
3. ‘Xe forms 3σ-bonds and 3π-bonds with three oxygens.
4. Shape of molecule is pyramidal with bond angle 103°.
   

b) Structure of XeO₄:
Xe is in sp₃ hybridisation four singma bonds and four dπ – pπ bonds. Shape of XeO₄ is tetrahedral.

Question 4.
Write the preparations of Xenon flourides.
Answer:
Xenon flourides : Xenon forms three binary fluorides, Xe F₂, XeF₄, and XeF₆ by the direct reaction of Xenon with fluorine under suitable conditions.

XeF₆ can also be prepared by the interaction of XeF₄ and O₂F₂ at 143 K.
XeF₄ + O₂F₂ → XeF₆ + O₂

Question 5.
Write the preparations of Xenon Oxides.
Answer:
Xenon Oxides: Xenon forms two oxides XeO₃ and XeO₄ with oxygen.
These oxides are formed by the hydrolysis of xenon fluorides.
6XeF₄ + 12 H₂O → 4 Xe + 2 XeO₃ + 24 HF + 3O₂
XeF₆ + 3 H₂O → XeO₃ + 6 HF

Question 6.
Give the formulae and describe the structures of a noble gas species, isostructural with
a) \(\mathrm{ICl}_4^{-}\)
b) \(\mathbf{I B r}_2^{-}\)
c) \(\mathrm{BrO}_3^{-}\)
Answer:
a) \(\mathrm{ICl}_4^{-}\) is also structural with XeF₄ and it has square planar shape.
b) \(\mathbf{I B r}_2^{-}\) is also structural with XeF₂ and it has linear shape.
c) \(\mathrm{BrO}_3^{-}\) is iso-structural with XeO₄ and it has tetrahedral šhape.

Question 7.
Write any two uses of Helium.
Answer:
Uses of Helium:

1. It is non inflammable and very light gas. Hence it is used in the balloons of Meteorological observations.
2. It is used in gas cooled nuclear reactors and used as cryogenic agent.
3. It is used as diluent for oxygen in modern diving apparatus.