All India Engineering / Architecture Entrance Examination (AIEEE)

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AIEEE 2009 Chemistry

Q. 9. In which of the following arrangements, the sequence is not strictly according to the property written against it?

1. B < C < O < N; increasing first ionization enthalpy
   
   
2. CO₂ < SiO₂ < SnO₂ < PbO₂: increasing oxidising power
   
   
3. HF < HCl < HBr < HI: increasing acid strength
   
   
4. NH₃ < PH₃ < AsH₃ < SbH₃: increasing basic strength

 Sol.: On moving down the group, the basic tendency of hydrides of group 15 decreases.

 Answer : (4)

 Q. 10. Knowing that the chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect?

1. Ln (III) hydroxides are mainly basic in character.
   
   
2. Because of the large size of the Ln (III) ions the bonding in its compounds is predominantly ionic in character.
   
   
3. The ionic sizes of Ln (III) decrease in general with increasing atomic number.
   
   
4. Ln (III) compounds are generally colourless.

Answer : (4)

 Q. 11. The set representing the correct order of ionic radius is:

Sol.:   On moving down the group, the ionic radius increases. In case of isoelectronic ions, more the charge on the ion, smaller will be its size.

Answer : (3)

 Q. 12. Buna–N synthetic rubber is a copolymer of:

Sol.: Buna–N is a copolymer of buta–1,3–diene and acrylonitrile.

Answer : (4)