Monday, 2 September 2013

p-block Important Questions

UNIT 7
The p – BLOCK ELEMENTS

VSA TYPE QUESTIONS (1 MARK)
1. In group 15 elements, there is considerable increase in covalent radius from N to P but small
increase from As to Bi. Give reason.
2. The tendency to exhibit – 3 oxidation state, decreases down the group in group 15 elements. Explain.
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. Assign a reason.
5. The ionization enthalpies of group 15 elements are higher than that of group 14 and 16 elements
in the corresponding period. Assign the reason.
6. The boiling point of PH3 is lesser than NH3. Why?
7. NO2 dimerises to form N2O4. Why?
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 hydrogenbond but PH3 does not?
11. Give disproportionation reaction of H3PO3?
12. How does NH3 acts as a complexing agent?
13. Why HF is the weakest acid and HI is strongest acid.
14. Explain Halogens are strong oxidising agent.
15. Why is Bi(V) a stronger oxidant than Sb(V)?
16. Why SF4 is easily hydrolysed, whereas SF6 is not easily hydrolysed?
17. Bond dissociation energy of F2 is less than that of Cl2. Why?
18. Write the reaction of PCl5 with heavy water.
19. How many P – O – P bonds are there in cyclotrimetaphosphoric acid?
20. In group 16, the stability of +6 oxidations state decreases and that of +4 oxidation state increases
down the group. Why?
21. Why we can not prepare HBr by heating KBr with sulphuric acid.
22. Explain sulphur disappears when boiled with aqueous solution of sodium sulphite.

23. Write the equation for the decomposition of hydrogen peroxide in the presence of finely divided
metal and MnO2 as catalyst.
24. Fluorine exhibit only –1 oxidation state whereas other halogens exhibit +ve oxidation states also.
Explain.
25. Arrange the following oxoacids of chlorine in increasing order of acidic strength.
HOCl, HOClO, HClO3, HOClO3
26. The majority of known noble gas compounds are those of Xenon. Why?
27. “Hypophosphorus acid is a good reducing agent.” Justify with an example.
28. Draw the structure of H4P2O7 and find out its basicity?
29. Arrange the following triatomic species in the order of increasing bond angle.
30. With what neutral molecule ClO– is isoelectronic.
31. Draw the structure of H2S2O8 and find the number of S–S bond if any.
32. What is cause of bleaching nature of Chlorine water? Explain it with chemical equation?
33. The negative value of electron gain enthalpy of fluorine is less than that of chlorine.
34. Which one of the following is not oxidised by O3. State the reason.
KI, FeSO4, K2MnO4, KMnO4
35. Complete the reaction Ca3P2 + H2O
SA (I) TYPE QUESTIONS (2 MARKS)
1. PCl5 is known but PI5 is not known .Why?
2. Why is red phosphorous denser and less chemically reactive than white phosphorous.
3. Give chemical reaction in support of the statement that all the bonds in PCl5 molecule are not
equivalent.
4. Account for the following :
(a) XeF2 has a straight line structure and not a bent angular structure.
(b) Phosphorous show marked tendency of Catenation.
5. Draw the structure of BrF3, XeOF4, XeO3, N2O3.
6. Write the conditions that favour the formation of ammonia gas along with the reactions involved
in Haber’s Process.
7. Write the chemical equations of the following reactions
(a) Glucose in heated with conc. H2SO4.
(b) Sodium Nitrate is heated with conc. H2SO4.
Complete the following reactions :
8. (i) (NH4)2 Cr2O7→
   (ii) NH4Cl aq NaNO2 aq→
9. (i) NH2CONH2 + H2O→
    (ii) FeCl3 (aq) + NH4OH→
10. (i) Ca3P2 + H2O →
     (ii) I2 + HNO3 (conc.) →
11. (i) Ba(N3)2 →
      (ii) 4H3PO3→
12. (i) PH4I + KOH→
    (ii) HgCl2 + PH3→
13. (i) PCl3 + 3H2O→
     (ii) S + H2SO4 (conc.) →
14. (i) Al2O3(s) + NaOH (aq) + H2O(l) →
    (ii) CuCl2+ HCl+ O2→
15. (i) Ca(OH)2 + Cl2→
      (ii) XeF4 + H2O→
16. (i) Na2SO3 + Cl2 + H2O→
      (ii) NaHCO3 + HCl→
17. (i) Complete Hydrolysis of XeF+ H O→
      (ii) Partial Hydrolysis of XeF+ H O→
18. (i) What is the covalency of N in N2O3?
     (ii) Explain why phosphorus forms pentahalide whereas nitrogen and bismuth do not?
19. (i) The acidic character increases from H2O to H2Te. Why?
      (ii) Dioxygen is a gas while sulphur (S8) is a solid. Why?
20. (i) Interhalogen compounds are more reactive than halogens. Why?
      (ii) Give one important use of ClF3.
21. (i) Write the composition of bleaching powder.
      (ii) What happens when NaCl is heated with conc. H2SO4 in the presence of MnO2. Write the
      chemical equation.

22. Arrange the following in the decreasing order of their basicity. Assign the reason :
PH3, NH3, SbH3, AsH3, BiH3.
23. A colourless and a pungent smelling gas which easily liquifies to a colourless liquid and freezes
to a white crystalline solid gives dense white fumes with ammonia. Identify the gas and write the
chemical equation for its laboratory preparation
24. Why are the following reactions regarded as disproportionation reactions?
      (a) P4 + NaOH + H2O→
      (b) HNO2→
25. Suggest reason why only known binary compounds of noble gases are fluorides and oxides of
     Krypton, Xenon and Radon.
26. Which fluorinating agent are often used instead of F2? Write two chemical equations showing their
     use as fluorinating agents.
27. (a) Hydrolysis of XeF6 is not regarded as a redox reaction. Why?
     (b) Write a chemical equation to represent the oxidising nature of XeF4.
28. Write Chemical equation :
       (a) Cl2 reacts with hot conc. solution of NaOH.
       (b) PtF6 and Xenon are mixed together.

SA (II) TYPE QUESTIONS (3 MARKS)
1. (i) How is HNO3 prepared commercially. Name the process.
    (ii) Write chemical equations of the reactions involved.
    (iii) What concentration by mass of HNO3 is obtained.
2. (i) How does O3 react with Lead sulphide, Write Chemical equation.
    (ii) What happens when SO2 is passed in acidified KMnO4 solution.
    (iii) Explain : behaviour of SO2 is similar to CO2.
3. Assign reason for the following :
     (i) Sulphur in vapour state exhibits paramagnetism.
    (ii) F2 is strongest oxidising agent among halogens.
    (iii) Inspite of same electronegativity oxygen forms hydrogen bond while chlorine does not.


4. Give appropriate reason for each of the following :
    (i) Metal fluorides are more ionic than metal chlorides.
   (ii) Perchloric acid is stronger than Sulphuric acid.
   (iii) Addition of chlorine to KI solution gives it a brown colour but excess of Cl2 makes it colourless.
[Hint : (i) According to Fajan’s Rule bigger ions more polarised than the smaller ion by a
        particular cation.
           (ii) Oxidation state of Cl in HClO4 is +7 white oxidation state of S in H2SO4 is +6, Hence OH
             bond easily breaks in the HClO4 molecule.
         (iii) 2KI + Cl2→ 2KCl + I2
                Excess 5Cl2 + I2 + 6H2O → 2HIO3 + 10 HCl Colourless.
5. Explain that :
(i) No chemical compound of Helium is known.
(ii) Bond dissociation energy of fluorine is less than that of chlorine.
(iii) Two S–O bonds in SO2 are identical.
9. (i) How O2 can be converted to O3
(ii) How Cl2 is manufactured by Deacon’s process.
(iii) How Cl2 reacts with hot and conc. NaOH.
7. Out of the following hydrides of Group 16 elements which will have :
(i) H2S (ii) H2O (iii) H2Te
(a) Lowest boiling point
(b) highest bond angle
(c) highest electropositive hydroden.
8. (i) How is XeO3 prepared from XeF6. Write the chemical equation for the reaction.
   (ii) D raw the structure of X eF 2, XeF4.
9. (i) Thermal stability of hydrides of group 16 elements decreases down the group. Why?
(ii) Compare the oxidising powers of F2 and Cl2 on the basis of bond dissociation enthalpy.
(iii) Write the chemical equation for the reaction of copper metal with conc. HNO3.
*10. An unknown salt X reacts with hot conc. H2SO4 to produce a brown coloured gas which intensifies on addition on copper turnings. On adding dilute ferrous sulphate solution to an aqueous solution of X and then carefully adding conc. H2SO4 along the sides of the test tube, a brown complex
Y is formed at the interface between the solution and H2SO4. Identify X and Y and write the chemical equation involved in the reaction.
11. Assign reason for the following :
(i) Noble gases have large positive value of electron gain enthalpy.
(ii) Helium has the lowest boiling point than any known substance.
12. Arrange the following in the order of the property indicated for each set –
(a) F2, Cl2, Br2, I2 – (Increasing bond dissociation energy).
(b) HF, HCl, HBr, HI (Increasing acid strength).
(c) NH3, PH3, ASH3, SbH3, BiH3 (Increasing base strength).
13. A transluscent while waxy solid (A) on heating in an inert atmosphere is converted to its allotropic
form (B), Allotrope (A) on reaction with very dilute aqueous NaOH/KOH liberates a highly poisonous
gas (C) having a rotten fish smell, with excess of chlorine forms D which hydrolyses to form
compound (E) identify the compounds (A) to (E).
14. Write balanced equation for the following reactions :
(a) Zn is treated with dilute HNO3.
(b) NaCl is heated with H2SO4 in the presence of MnO2.
(c) Iodine is treated with conc. HNO3.
15. X2 is a greenish yellow gas with pungent offensive smell used in purification of water. It partially
dissolves in H2O to give a solution which turns blue letmus red, When X2 is passed through NaBr
Solution, Br2 is obtained.
(a) Identify X2, Name the group to which it belongs.
(b) What are the products obtained when X2 reacts with H2O? Write chemical equation.
(c) What happens when X2 reacts with conc. NaOH. Give equation.
16. Assign the appropriate reason for the following:
(a) Nitrogen exist as diatonic molecule and phorphorous as P4, Why?
(b) Why does R3P = 0, exist but R3N = 0 does not (R = alkyl group).
(c) Explain why fluorine forms only one oxoacid, HOF?

LONG ANSWER TYPE QUESTIONS (5 MARKS)
1. How is PH3 prepared in the laboratory? How is it purified? How does the solution of PH3 in water
react on irradiation with light and on absorption in CuSO4? How can you prove that PH3 is basic
in nature?
Write the chemical equations for all the reactions involved.
2. Assign a possible reason for the following :
(a) Stability of +5 oxidation state decreases and that of +3 oxidation state increases down the
group 15 elements.
(b) H2O is less acidic than H2S.
(c) SF6 is inert while SF4 is highly reactive.
(d) H3PO2 and H3PO3 act as good reducing agents while H3PO4 does not.
(e) Noble gases have comparatively large size in their respective period.
3. (a) How is XeF6 prepared from the XeF4? Write the chemical equation for the reaction.
 (b) Deduce the structure of XeF6 from VSEPR theory.
(c) How does XeF2 reacts with PF5?
(d) Give one use each of helium and Neon.
(e) Write the chemical equation for the hydrolysis of XeF4.
4. (a) Why does nitrogen show anomalous behaviour? Discuss the trend of chemical reactivity
of group 15 elements with.
(a) Oxygen (b) Halogens (c) Metals
(b) H3PO2 is a dibasic acid. Why?
5. (a) Arrange the following in the order of their increasing acid strength.
(a) Cl2O7, SO2, P4O10
(b) How in N2O gas prepared.
(c) Give one chemical reaction to show O3 is an oxidising agent.
7. A white waxy, translucent solid, M, insoluble in water but soluble in CS2, glows in dark. M
dissolves in NaOH in an inert atmosphere giving a poisonous gas (N). Also M catches fire to give
dense white fumes of O :
(a) Identify M, N and O and write the chemical equations of the reactions involved.
(b) M exist in the form of discrete tetrahedral molecule. Draw its structure.
(c) M on heating at 573 K is changed into other less reactive form, Q, which is non-poisonous,
insoluble in water as well as in CS2 and does not glow in dark, Identify Q and draw its
structure.
9. Give reason for each of the following :
(a) Molten alumina is a poor conductor of electricity.
(b) Ammonia is a good complexing agent.
(c) Bleaching by SO2 is temporary.
(d) PCl5 is ionic in solid state.
(e) Sulphur in vapour form exhibits paramagnetism.
p-BLOCK ELEMENTS.

01. Why Cl2 has more EA than F2.
02. H2O is a liquid while H2S is a liquid at room temperature . Why?
03. Why O2 cannot show +4 and +6 oxidation states where as S gives.
                                                OR
       Why OF6 is not formed but SF6 formed.
04. Which of the two is more covalent- SbCl3 or SbCl5.
05. In SnCl3 and SnCl5 --- which one is solid and why.
06. Arrange the species in increasing order of their boiling points  H2O, H2S, H2Se, H2Te.             
07. What is inert pair effect?
08.              Tl forms TlCl while Al forms AlCl3 though both Al and Tl belongs to the same  group why?
                        09. PbCl2 is more stable than PbCl4 while SnCl4 is more stable than  SnCl2? Why
10. Define back bonding.
11. Sulphur forms SF6 but not SH6 why?
12. Write the structure H4P2O7, H4P2O6
13. What are interhalogen compounds? Write its 2 properties?
14. Arrange the species in increasing acidic strengths HOCl, HClO2, HClO3 HClO4.
15. Compare the oxidising powers of Cl2, F2 based on bond energies.
16. Draw the structures of ClO 2- and ClO 4- species.
17. N2 is a gas while others are solids in the same family.Why
18. 2 PF5 + F2
19. What happens when PH3 reacts with NaOCl. Give chemical equation.
20. Draw the structures of nitrogen oxide N2O5 and N2O3.
21. Balance the following reaction-    Pb(NO3)2 + heat
22. Why is P4O10  used as a dehydrating agent?
23.  How do thermal stability vary fom top to bottom for the  hydrides of 16th group elements.
24. Give two important uses of selenium.
25.  How the acidity of hydrides of group 16 vary from 'S' to Te.
26. What is the shape of SF4 molecule.
27. Why do interhalogen compounds are more reactive than halogens.
28. Arrange the following in the decreasing order of property indicated.
HF, HCl, HBr                 Ionic character.
                        CH4, SiH4, GeH4          boiling point.
                        HF, HCl, HBr, HI           acid strength.
29.              Complete the following equations.
                        XeO3  +  Xe  +  H+
                        BrO3 +  F2 +  OH-
30. What is the main use of ClO2 and Cl2O?
31. XeO3 is unstable and explosive? Give reasons?
32. Draw the structures of XeOF4, XeF6 also write their shapes?
33. Complete and balance the following equations.
                      a. XeF4 + H2O
                      b. XeF2 + PF5
                      c. XeF4 + Sb 3+
34. Which of the three is strongest oxidising agents ClO4-, BrO4- & IO4-.
35.              XeF2 is linear despite of its sp3d hybridisation. Why?
36.              Why O2 cannot show +4 and +6 oxidation states where as S gives.
                                                OR
       Why OF6 is not formed but SF6 formed.
37.               Which of the two is more covalent- SbCl3 or SbCl5.
38.               In SnCl3 and SnCl5- which one is solid and why.
39.              BeCl2 fumes in moist air? Why
40.              Complete the following:
            PbO2 + HNO3→
            NaBH4 + I2    →
            Pb(NO3)2→
            NH3 + NaOCl→
            XeF2 + KF→
            SbCl3 + H2O→
            XeF6 + H2O→
            IO3- + I-  + H+→
            BrO3- + F2 +OH-→
            B2H6 + LiH→
            LiH + BF3→
            KClO3 + I2. →
K + O2→
      Na + O2→
            BF3 + LiH→
            NaH + B2H6→
            BCl3 + H2O→
41.  Tl forms TlCl while Al forms AlCl3 though both Al and Tl belongs to the same group  .why?
42.   PbCl2 is more stable than PbCl4 while SnCl4 is more stable than  SnCl2? why
43.  BBr3 is more acidic than BF3 why?
44.  Define back bonding.
45.  Write four points for how B shows similarities with silicon?
46.  What are silicones ? Give its two properties?
47.  Sulphur forms SF6 but not SH6 why?
48.  Write the structure H4P2O7, H4P2O6
49.  What are interhalogen compounds? Write its 2 properties?
50.  Arrange the species in increasing acidic strengths HOCl, HClO2, HClO3 , HClO4.
51.  Compare the oxidising powers of Cl2, F2 based on bond energies.
52.  Draw the structures of ClO2- and ClO4- species.
53.  What happened when PH3 reacts with NaOCl. Give chemical equation.
54.  Draw the structures of nitrogen oxide N2O5 and N2O3.
55.  Why do P4O10 used as a dehydrating agent?
56.  How do thermal stability vary from top to bottom for the  hydrides  of 16th group elements.
57.  Give two important uses of selenium.
58.  How the acidity of hydrides of group 16 vary from 'S' to Te.
59.  What is the shape of SF4 molecule.
60.  Why do interhalogen compounds are more reactive than halogens.
61.  Arrange the following in the decreasing order of property indicated.
            HF, HCl, HBr             Ionic character.
            CH4, SiH4, GeH4          boiling point.
            HF, HCl, HBr, HI         acid strength.
62.  Complete the following equatioms.
63.  Draw the structures of XeOF4, XeF6 also write their shapes?
64.  Complete and balance the following equations.
            a.         XeF4 + H2O
            b.         XeF2 + PF5
            c.         XeF4 + Sb3+
            d.         XeF6 + Mf
 


Q. 1. There is a considerable increase in covalent radius from N to P but from As to Bi only a small change is observed.
Q. 2. Ionisation enthalpy of group 15 elements is much higher than that of group 14 elements.
Q. 3. Ionic radius of Sb and Bi are very less when compared to the ionic radius of N,P and As.
Q. 4. Metallic character of group 15 elements decreases on going down the group.
Q. 5. Tendency to show +3 oxidation states in group 15 decreases on going down the group.
Q. 6. Nitrogen cannot form penta halides.
Q. 7. Nitrogen exhibits bonding while heavier members exhibit bonding.
Q. 8. N2 is a gas while P4 is a solid.
Q. 9. Catenation tendency is weaker in nitrogen.
Q. 10. N2 molecule is chemically inert while white phosphorus is more reactive.
Q. 11. In group 15, +3 oxidation state is more stable than +5 oxidation state on going down the group .
Q. 12. R3 P=O is known but R3 N=O is unknown.
Q. 13. Basicity of hydrides NH3> PH3 > AsH3 > SbH3 > BiH3
Q. 14. Stability of hydrides NH3> PH3 > AsH3 > SbH3 > BiH3
Q. 15. Reducing character of hydrides NH3< PH3 <AsH3 < SbH3< BiH3
Q. 16. The oxides in higher oxidation states of group 15 elements are more acidic than that of lower oxidation state.
Q. 17. Basicity of group 15 oxides increases on going down the group.
Q. 18. PCl5 is more covalent than PCl3.
Q. 19. PCl5 is more covalent than PF5.
Q. 20. All the five bonds in PCl5 are not equivalent.(Or) PCl5 is more reactive than PCl3.
Q. 21. Both PCl3 and PCl5 fumes in air.
Q. 22. PH3 has lower boiling point than NH3.
Q. 23. NH3 acts as a lewis base.
Q. 24. NO2 molecule dimerise to become N2O4.
Q. 25. Aluminium is rendered passive in concentrated HNO3.
Q. 26. Concentrated HNO3 becomes yellow when exposed to light.(Or) concentrated HNO3 is an oxidizing agent.
Q. 27. White phosphorus is more reactive than red phosphorus. Black phosphorus is least reactive.
Q. 28. Bond angle in PH3+ is higher than that of PH3.
Q. 29. HNH bond angle in NH3 is less than the tetra hedral bond angle of 109.50.
Q. 30. Bond angles of PH3,  AsH3 and SbH3 are closer to 900.
Q. 31. H3PO4 is tri protic, H3PO3is diprotic while H3PO2 is mono protic.
Q. 32. H3PO2 is a good reducing agent.
Q. 33. H3PO2 is a stronger reducing agent than H3PO3.
Q. 34. NO is an odd electron molecule but does not dimerise to give N2O2.
Q. 35. Sulphur has very high boiling and melting point when compared to oxygen.
Q. 36. In group 16 tendencies to show -2 oxidation state decreases on going down the group.
Q. 37. In group 16 +4 oxidation state become more stable than +6 oxidation state on going down the group.
Q. 38. Oxygen can show a maximum covalency of 4 and it can not form hexa valent compound.
Q. 39. Acidity of group 16 hydrides H2O<  H2S < H2Se < H2Te.
Q. 40. Reducing character of group 16 hydrides H2O<  H2S < H2Se < H2Te
Q. 41. Boiling point of H2O is higher than that of H2 S.
Q. 42. Sulphur exhibit +6 oxidation state when it combines with fluorine.
Q. 43. SF6 is exceptionally stable or it can not be hydrolysed easily.
Q. 44. SF6is known while SCl6 is unknown.
Q. 45. SF6 is known while SH6 is unknown.
Q. 46. H2O is a liquid while H2S is a gas.
Q. 47. MnO is basic while Mn2O7 is acidic.
Q. 48. O3 is thermo dynamically unstable than O2 (or) . O3 in higher concentration is explosive.
Q. 49. NO gas depletes ozone layer.
Q. 50. Sulphur in vapour state is paramagnetic.
Q. 51. HCl and HNO3 are prepared by reacting NaCl and NaNO3 respectively with H2SO4  while HBr and HI can’t be prepared by this method.
Q. 52. Cane sugar chars in concentrated sulphuric acid.
Q. 53. Concentrated sulphuric acid is a good oxidizing agent.
Q. 54. Two S-O bonds in SO2 are equivalent.
Q. 55. Ka2 of H2SO4 is <<<1.
Q. 56. Halogens have maximum negative electron gain enthalpy in each period.
Q. 57. Fluorine has lesser negative value of electron gain enthalpy than chlorine.
Q. 58. All halogens are colored.
Q. 59. F2 has smaller enthalpy of dissociation than Cl2.
Q. 60. Fluorine has lesser negative value of electron gain enthalpy than chlorine but fluorine is a stronger oxidizing agent than chlorine.
Q. 61. Fluorine shows only - 1 oxidation state. Other halogens can exhibit positive oxidation state.
Q. 62. Halogens show positive oxidation state when they combine with oxygen and fluorine atoms.
Q. 63. Halogens are good oxidizing agent and oxidizing power (reactivity) decreases with the increase in atomic number.
Q. 64. Most of reactions of fluorine are exothermic.
Q. 65. HF is a liquid while other hydrogen halides are gases.
Q. 66. HF has highest boiling point while HCl has lowest boiling point among hydrogen halides.
Q. 67. Acidity of hydrogen halides HF < HCl< HBr< HI
Q. 68. Thermal stability of hydrogen halides HF > HCl > HBr > HI
Q. 69. Thermal stability of group 16 hydrides H2O > H2S > H2Se > H2Te
Q. 70. OF2 is fluoride of oxygen and not oxide of fluorine.
Q. 71. Oxygen and chlorine has similar electro negativity. Oxygen form hydrogen bonding but not chlorine.
Q. 72. Ionic character of halides MF>MCl>MBr>MI
Q. 73. Electron gain enthalpy of O   → O- is “ 141 KJ/mole and O→  O2- is + 702 KJ/mole.
Large number of oxides having O2- is known and not O-.
Q. 74. In metal halides, halides in higher oxidation state of the metal is more covalent than
the one in lower oxidation state.(PbCl4 is more covalent than PbCl2)
Q. 75. Inter halogen compound is more reactive than the halogens from which it is formed.
Q. 76. Chlorine is a powerful bleaching agent.
Q. 77. HCl reacts with Fe to give FeCl2 and not FeCl3
Q. 78. Fluorine forms only one oxo acid HOF
Q. 79. Acidity of oxo acids HClO4> HClO3> HClO2> HC1O.
Q. 80. Acidity of oxo acids HOCl>HOBr>HOI
Q. 81. Oxidizing power of HClO4> HClO3> HClO2> HClO
Q. 82. Fluorine form fluoride of oxygen while other halogens form oxides of halogen.
Q. 83. Group 18 elements are chemically unreactive.
Q. 84. Group 18 elements have very high ionization enthalpy and it decreases on going down the group.
Q. 85. Group 18 elements have positive value of electron gain enthalpy.
Q. 86. Group 18 elements have lower value of boiling and melting point and it increases on going down the group.
Q. 87. Group 18 elements have larger atomic radius.
Q. 88. Bartlett synthesized XePtF6 from his knowledge of earlier known compound O2PtF6.
Q. 89. Xenon forms noble gas compounds.
Q. 90. Xenon forms compounds only with oxygen and fluorine.

IMPORTANT REACTIONS

1. (NH4)2SO4 + 2KOH  K2SO4 + 2H2O + 2NH3

2. Mg3N2 + 6H2O       3Mg(OH)2 + 2NH3

3. FeC13(aq) +  3NH4OH(aq)  Fe2O3.xH2O(s) + NH4CI(aq)

4. ZnSO4(aq) + 2NH4OH(aq)   Zn(OH)2(s) + (NH4)2SO4(aq)

5. NH4NO3    N2O + 2H2O

6. 2NO + N2O4  2N2O3
7. 2Pb(NO3)2   4NO2 + 2PbO + O2

8. 2HNO3 + P2O5     N2O5 + 2HPO3

9. NaNO3 + H2SO4   NaHSO4 + HNO3

10. 3NO2(g) + H2O(l) 2HNO3(aq) + NO(g)

11. 4Zn + 1OHNO3(dil.) 4Zn(NO3)2 + N2O + 5H2O
12. Zn + 4HNO3(conc.)  Zn(NO3)2 + 2NO2 + 2H2O

13. 3Cu + 8HNO3(dil.)  3Cu(NO3)2 + 2NO + 4H2O
14. Cu + 4HNO3(conc.) Cu(NO3)2 + 2NO2 + 2H2O
15. C + 4HNO3 2H2O + 4NO2 + CO2
16. S8 + 48HNO3(conc.) 8H2SO4 + 16H2O + 48NO2
17. P4 + 2OHNO3(conc.) 4H3PO4 + 20NO2 + 4H2O
l8.  I2  +   10HNO3  2HIO3 + 10NO2 + 10H2O
19. P4 + 3NaOH + 3H2O  PH3 + 3NaH2PO2 (sod. hypophosphite)
20. P4 + 5O2P4O10
21. Ca3P2 + 6H2O 3Ca(OH)2 + 2PH3
22. Ca3P2 + 6HC13CaCI2 + 2PH3
23. 3CuSO4 + 2PH3 Cu3P2 + 3H2SO4
24. 3HgC12 +2PH3 Hg3P2 +6HCI
25. PH3 +HBr PH4Br
26. P4 + 6Cl2(dry, limited) 4PC13
27. P4 + 8SOC12 4PCI3 + 4SO2 + 2S2C12
28. PCI3 + 3H2O  H3PO3 + 3HCI
29. 3C2H5OH + PCI3  3C2H5C1 + H3PO3
30. 3CH3COOH + PCl3  3C2H3COCI + H3PO3
31. P4 + l0Cl2(dry, excess)  4PC15
32.P4 + 10SO2C12 4PC15 + 10SO2
33.PCl5 (moist air)POCI3 + 2HC1 (hydrolysis) H3PO4 +5HCl
34. 5SO2 + 2MnO-4 + 2H2O 5SO42- + 4H+ + 2Mn2+
35. C2H5OH + PCl5  C2H5CI + POCl3 + HCI
36. CH3COOH + PCl5 CH3COCI + POCI3+HC1
37. 2Ag + PCl5 2AgCl + PCI3
38. Sn + 2PC15 SnCI4 + 2PC13
39. PCI3 + 3H2O  H3PO3 + 3HCI
40. PC15  PCl3 + Cl2
41. PCl5 + D2O  POCI3 + 2DCl
42. 4H3PO3  3H3PO4 + PH3
43. 4AgNO3 + 2H2O + H3PO2  4Ag + 4HNO3 + H3P04
44. 2KClO3(s) 2KC1(s) + 3O2(g)
45. 2H2O2(aq) 2H2O(l) + O2(g)
46. 2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g)
47. 2SO2(g) + O2(g) 2SO3(g)
48. 4HCI(g) + O2(g) 2Cl2(g) + 2H2O(g)
49. A12O3 (s) + 6HC1(aq) + 9H2O(l)2[Al(H2O)6]3+ (aq) + 6Cl-(aq)
50. A12O3 (s) + 6NaOH(aq) + 3H2O 2Na3[Al(OH)6](aq)
51. PbS + 4O3  PbSO4 + 4O2
52. 2K1+H2O+O3  2KOH + I2+ O2
53. NO+O3  NO2+O2
54. SO32-(aq) + 2H+(aq) H2O + SO2(g)
55. 4FeS2 (s) 11O2(g)  2Fe2O3 (s) + 8S02(g)
56. 2NaOH + 2SO2 + H2O 2NaHSO3
57. SO2(g) + C12(g) SO2C12(l)
58. 2Fe3++ SO2 + 2H2O 2Fe2++ SO42- + 4H+
59. 2KCI + H2SO4  2HCI + K2SO4
60. C12H22O11 12C + 11H2O
61. Cu + 2 H2SO4 (conc.) CuSO4 + SO2 + 2H2O
62. 3S + 2H2SO4(conc.)  3SO2 + 2H2O
63. C + 2H2SO4 (conc.)  CO2 + 2 SO2 + 2H2O
64. CaF2 + H2SO4  CaSO4 + 2HF
65. F2+2C1-2F-+C12
66. Br2 + 2I- 2Br-+I2
67. C12(g) + H2O(l) HCI(aq) + HOCI(aq)
68. 2F2 (g) + 2H2O(l) 4H+ (aq) + 4F- (aq) + O2(g)
69. 4I- (aq) + 4H+(aq) + O2(g)  2I2(s) + 2H2O(l)
70. MnO2+ 4HCI MnCI2+C12+ 2H2O
71. 4NaCI + MnO2 + 4H2SO4  MnCI2 + 4NaHSO4 + 2H2O
72. 2KMnO4+16HCI 2KCl + 2MnCI2 + 8H2O + 5Cl2
73. 4HCl + O2  2C12 + 2H2O
74. 2 Fe + 3Cl2 2FeCl3
75. S8 + 4C12 4S2C12
76. H2S+C12 2HC1+S
77. C10H16 + 8C12 16HC1 + 10C
78. 8NH3 + 3C12 6NH4CI + N2
                   (excess)
79. NH3 + 3Cl2  NCl3 + 3HC1
80. 2NaOH + Cl2  NaCI + NaOC1 + H2O
      (cold and dilute)

81. 6 NaOH + 3Cl2 5NaCI + NaCIO3 + 3H2O
        (hot and conc.)
82. 2Ca(OH)2 + 2C12  Ca(OCI)2 + CaCl2 + 2H2O
83. 2FeSO4 + H2SO4 + Cl2  Fe2(SO4)3 + 2HC1
84. Na2SO3 + C12+H2O Na2SO4 + 2HCI
85. SO2 + 2H2O + Cl2 H2SO4 + 2HCI
86. I2 + + 6H2O2HIO + 1OHCl
87. Au + 4H+ + NO3- + 4Cl-   AuCl4- + NO + 2H2O
88. XeF4 + O2F2  XeF6 + O2
89. 2XeF2(s) + 2H20 2Xe(g) + 4HF(aq) + O2
90. XeF2 + PF5 XeF+  [PF6]-
91. XeF4 + SbF5 [XeF3]+ [SbF6]-
92. XeF6 + NaF  Na [XeF7]
93. 6XeF4 + 12H2O  4Xe + 2XeO3 + 24 HF + 3O2
94. XeF6 + 3H2O  XeO3 + 6HF
95. PbO2 + 2HNO3  Pb(NO3) + H2O + ½O2
96. IO3- + 5I- + 6H+ 3I2 + 3H2O
97. BrO3-+ F2 + 2OH- BrO4- + 2F- + H2O
98. 2NH3 + NaOC1 N2H4 + NaC1 + H2O
99. Ca(OCI)2 + HCI CaCl2 + 2H2O + 2C12
100.Cu2+(aq) + 4NH3(aq) [Cu(NH3)4](OH)2
                                        (excess)

The square diagram is for -->

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