CBSE Class 12 Chemistry notes and questions for The p block Elements Part D

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CBSE Basic Concepts for Class XII Chemistry notes and questions for The p block Elements Part D.Based on CBSE and CCE guidelines. The students should read these basic concepts to gain perfection which will help him to get more marks in CBSE examination.


1. In group 15 elements, there is considerable increase in covalent radius from N to P but small increase from As to Bi. Why?

[Hint : Due to completely filled d- and / or f-orbitals in As, Sb and Bi.

2. The tendency to exhibit – 3 oxidation state, decreases down the group in group 15 elements. Explain.

[Hint : Due to increase in size and decrease in electronegativity down the groups].

3. Maximum covalence of Nitrogen is ‘4’ but the heavier elements of group 15 show covalence greater than ‘4’. Why?

4. Nitrogen exists as a diatomic molecule with a triple bond between the two atoms, whereas the heavier elements of the group do not exist as E2 at room temperature. Assign a reason.

[Hint : p – p multiple bonds are formed by N due to its small size.]

5. The ionization enthalpies of group 15 elements are higher than those of corresponding members of group 14 and 16 elements. Assign the reason.

6. The boiling point of PH3 is lesser than NH3. Why?

7. NO2 dimerises to form N2O4. Why?

[Hint : Due to presence of odd electron on N]

8. Draw the structure of N2O5 molecule.

9. How does ammonia solution react with Ag+ (aq)? Write the balanced chemical equation.

10. Why does NH3 forms intermolecular hydrogen bonds whereas PH3 does not?

[Hint : Due to strong electronegativity, small size of Nitrogen atom and presence of lone pair of electrons on N atom]

11. Write disproportionation reaction of H3PO3?

12. How does NH3 acts as a complexing agent?

[Hint : Metal hydroxides are dissolved in excess of NH4OH. Ammonia acts as a Lewis base].

13. Why HF is the weakest acid and HI is the strongest.

Please refer to attached file for CBSE Class 12 Chemistry notes and questions for The p block Elements Part D

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