Monday, August 20, 2012

Formic acid

formic acid give tollen test because it contain aldehyde group(H---CO--OH

Sunday, January 29, 2012

PBlock

yellow for 11th class
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

P-BlockPart-2

1. Why is bond dissociation energy of F2 less than that of Cl2?
2. Why is I2 more soluble in KI than in water?
3. Why is helium used for inflating aeroplane tyres?
4. Complete & balance the following 450K chemical equations:-
450K
(i) BF3 + LiH
 (ii) BrO3- + F2 + OH-
39. Complete & balance the following equation:-Ca3P2 + H2O
40. Give reasons for the following observations:-
(i) The molecule N(CH3)3 & N(SiH3)3 have different shapes.
(ii) BF3 is weaker Lewis acid than BCl3.
41. Why are inter halogen compounds more reactive than the related elemental halogens?
42. Complete the following chemical equations:-
Cu powder
(i) RCl + Si
 (ii) XeF6 + H2O

43. Arrange the following in decreasing order of property indicated:-
(i) H2O, H2S,H2Se, H2 Te boiling point
(ii) F2,Cl2,Br2,I2 bond energy
(iii) MF,MCl,MBr,MI ionic character of the bond.
(iv) NH3, PH3,AsH3,SbH3 base strength
44. Give reasons for the following:-
(I) PH3 is a weaker base than NH3 (ii) In group 14 of the periodic table of elements, the tendency to catenate decreases down the group.
45. Arrange the following compounds in decreasing order of property indicated against each. Give reason for your answer:-
(i) H2O, H2S,H2Se, H2Te (B.P)(ii) BCl3,AlCl3,GaCl3,InCl3,TiCl3 (Stability of +3 oxidation state)
46. What is meant by catenation? How does catenation tendency for elements of group 14 vary?
47. How is XeO3 prepared? Write the related chemical equation. Draw the structure of XeO3.
48. Complete the following chemical equations:-(i) XeF4+SbF5 (ii) NH3+NaOCl (iii) SbCl3+H2O
49. Complete the following reactions giving balanced reactions:-
(i) PCl3 + H2O
 (ii) SbCl3+H2O (iii) As+Cl2
(iv) H3AsO4(aq) + Zn(s) + H+ (aq)
50. Why is H3PO3 diprotic?
51. Complete the following reactions:-
(i) I2 +NaClO3
 (ii) I2+S2O32-
(iii) XeF2 + H2O
 (iv)Br2+NaI
52. Which of the following is acidic & why ? SiO2, Al2O3, PbO2, SnO2
53. Gallium has higher I.E. than Al. Explain.
54. Arrange the following in order of the property mentioned:-
(i) PH3, NH3, SbH3,AsH3 (increasing basic strength
(ii) KCl,MgCL2, CaCl2, BaCl2 (increasing ionic character
(iii) HClO4, HClO3, HClO2 (increasing oxidizing ability)
55. What happens when: (i) phosphorus is boiled with caustic alkali? (ii) Potassium reacts with acetylene
56. Complete & balance the following:- (i) PbO2 + HNO3 (ii) NaBH4+I2 (iii) Ca3P2+H2O
57. Complete the following:- (i) Cl2+NaOH (cold & dil.) (ii) F2+NaOH(hot & conc.) (iii) F2+H2O(hot)
58. How is lithium aluminum hydride (LiAlH4), prepared? What is its important use ?
59. Describe the contact process for the manufacture of sulphuric acid.
60. Write balanced equation for the following reaction:- Tin is heated with an excess of chlorine gas.
61. Write balanced equation for the following reactions:-
(a) Ca3P2 + H2O (b) P4H10+H2O
(c) As4+Cl2(excess) (d) P4+KOH+H2O
(e) NaCl is heated with H2SO4 in presence of MnO2 (f) Cl2 gas is passed through NaI in water.
(g) SiO2 reacts with HF (h) NaClO3 is treated with SO2 (i) Iodine is treated with conc. HNO3
(j) NH3+NaOCl (k) XeF4+SbF5
(l) SbCl3 + H2O (m) IO3- + I-+H+
(n) XeF6+PF5 (n) PbO2+HNO3
(o) NaBH4+I2 (p) Ca3P2+H2O
(q) Pb(NO3)2 undergoes heating
(r) BrO3-+F2+OH-
Describe a method for the isolation of elemental phosphorus from Ca3(PO4)2
62. Calculate the volume of 0.1M NaOH solution required to neutralize the solution produced by dissolving 1.1g of P4O6 in water.
63. Using VSEPR theory, predict the probable structures of SO32-, IF6-, XeF2, ClO4-,ICI4- & IBr2-
64. Describe the contact process for the manufacture of sulphuric acid.
65. How would you prepare(a) Cl2 gas in the laboratory (b) HF from CaF2 (c) Br2 from sea water )d) I2 from NaIO3 (e) HBr from NaBr?
66. Arrange the following in order of properties indicated for each set:-
(a) F2, Cl2, Br2, I2 Increasing bond energy
(b) HF, HCl, HBr, HI- Increasing acidic strength & B.P.
(c) MF, MCl, MBr, MI- Increasing ionic character (d) As2O3, ClO2, GeO2, Ga2O3 Increasing acidity
(e) NH3, PH3, AsH3, SbH3 Increasing acidic character (f) HOCl, HOBr, HOI Increasing acidic strength
(g) H2O, H2S, H2Se, H2Te Increasing boiling point & acidic nature
(h) HOCl, HClO2, HClO3, HClO4 Increasing oxidizing nature
(i) HIO4, HBrO4,HClO4 Increasing oxidizing nature
67. Explain: (a) Sulphur in gaseous state shows paramagnetic behaviour
(b) F2 is stronger oxidizing agent than Cl2 but Cl electron affinity is more than that of F2. CO2 is gas, SiO2 is solid (c) PbO2 is stronger oxidizing agent than SnO2. (d) NF3 is an exothermic compound but NCl3 is an endothermic compound. (e) Anhydrous AlF3 has higher melting point than AlCl3. (f) SnCl2 is solid & SnCl4 is liquid. (g) HF is stored in wax coated bottle.(h) Nitric acid becomes yellow in colour on long standing.
68. X2 is greenish yellow gas with an offensive smell used in water purification. It partially dissolves in water to give a solution which turns blue litmus to red. When X2 is passed through NaBr solution, Br2is obtained. (a) Identify X2. (b) What are the products formed when X2 reacts with H2O. Write chemical equation. (c) What happens when X2 reacts with hot & conc. NaOH
69. Which allotropes of Selenium conduct electricity?
70. What is Tin plague?
71. Why PbI2 is coloured ?
72. Why PbI4 does not exist ?
73. Discuss halogen family on the following points: (i) Hydride (ii) Oxide (iii) Oxy acid (iv) Interhalogen compound