PBlock

1. Give reasons for the following:-
(a) PH3 is a weaker base than NH3
(b) In group 14 of periodic table of elements, the tendency to catenation decreases down the group
2. Which has the larger bond angle H2S or H2O & why ?
3. Draw & name the molecular shape of SF6.
4. How is orthoboric acid related to metaboric acid?
5. What property of anhydrous AlCl3 makes it a very good preparative reagent in organic chemistry?
6. Although pure silicon is an insulator, then how does it behave as semiconductor on heating?
7. What happens when XeF6 is hydrolyzed ?
8. Complete the reaction: XeF4 + H2O
9. What is inert pair effect?
10. Why does oxygen not show an oxidation state of +4 & +6 like sulphur?
11. Name the product formed when dichloro dimethyl silane is hydrolyzed?
12. What is general formula of silicones?
13. Name the geometry of XeOF4 and XeO3-.
14. What is the state of hybridization in CO32-?
15. What is the oxidation state of Ni in [Ni(CO)4]?
16. CO2 is a gas while SiO2 is solid at room temperature. State a reason for this.
17. Complete the reaction: XeF4 + H2O
18. What is inert pair effect?
19. Give the reason which prompted Barlett to prepare first noble gas compounds.
20. Why is N2 not particularly reactive?
21. Write two uses of elemental selenium.
22. Why is that aluminium metal cannot be obtained by electrolysis of an aqueous solution of a salt of aluminium?
23. Graphite is used as solid lubricant but charcoal is not, why?
24. Identify X in the following reaction:
Cl2 + 2X- 2Cl- + X2
25. What are silicates?
26. What are allotropes of sulphur?
27. B to Tl, +1 oxidation state becomes more stable, why?
28. SiCl4 gets hydrolysed, CCl4 does not. Why?
29. Why is NH3 good complexing agent?
30. Why is PbCl4 good oxidizing agent?
31. Sulphur disappears when boiled with sodium sulphite. Why?
32. What are chalcogens? Why are group 16 elements called chalcogens?
33. Why is F2 most reactive among halogens?
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