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Unit: 7- The p –Block Elements
I. Account for the following
1. Ammonia has higher boiling point than Phosphine.
2. Bi(V) is a strong oxidizing agent than Sb (V)
3. + 3 oxidation state becomes more and more stable from As to Bi in the group
4. The stability of +3 state increases down the group in group 15 of the periodic table.
5. The +5 oxidation state becomes less stable down the group 15 of the periodic table
6. Phosphorus shows greater tendency for catenation than Nitrogen.
7. Phosphorous ,P4 is much more reactive than Nitrogen N2
8. All the bonds in the molecules of PCl5 are not equal.
9. NH3 is stronger base than PH3.
10. PH3 is weaker base than NH3
11. PH3 forms bubbles when passed slowly in water but NH3 dissolves.
12. Nitrogen does not form pentahalides.
13. Tendency to form pentahalides decreases down the group in group 15 of the periodic table
14. In solid state PCl5 exists as Ionic compound.
15. PCl4 + is likely to exist but PCl4- is likely not to exist.
16. NH3 act as ligand.( Lewis base)
17. Ammonia(NH3) has greater affinity for protons than phosphine PH3
18. In the structure of HNO3 ,the N-O bond (121pm) is shorter than N-OH bond(140pm)
19. The N – O bond in NO2- is shorter than the N – O bond in NO3-
20. NCl3 is an endothermic compound while NF3 is an exothermic one
21. Red phosphorous is less reactive than white Phosphorous
22. CN¯ ion is known but CP¯ ion is not known.
23. H3PO2 and H3PO3 act as as good reducing agents while H3PO4 does not.
24. NO2 is coloured but N2O4 is colourless.
25. NO2 dimerises to form N2O4
26. Nitric oxide becomes brown when released in air.
27. Nitric oxide is paramagnetic in gaseous state but the solid obtained on cooling it is diamagnetic
28. Bond angle in PH4 + is higher than that in PH3
29. Pentahalides of group 15 are more Covalent than trihalides
30. The first ionization energy of nitrogen is greater than oxygen.
31. H3PO3 is diprotic acid.
32. Nitrogen exists as diatomic molecule and phosphorus as P4.
33. NH3 is basic while BiH3 is only feebly basic
34. PF5 is known while NF5 is not known.
35. Sulphur vapours exhibits paramagnetism.
36. In solution of sulphuric acid in water the Ka2 << Ka1.
37. Sulphur shows greater tendency for catenation than selenium
38. Sulphur has greater tendency for catenation than oxygen.
39. H2O is a liquid while H2S is a gas
40. H2S is less acidic than H2Te.
41. The negative value of electron gain enthalpy of oxygen atom is less than that of sulphur
42. SF6 is much less reactive than SF4
43. All the bonds in the molecules of SF4 are not equal
44. SF6 is kinetically an inert substance.
45. H2S is more acidic than H2O.
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