PYQ Vault

Chemistry · Textbook solutions

Elements of Groups 16, 17 and 18

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. Plus every board question asked from this chapter. · 62 questions

7. Elements of Groups 16, 17 and 18 — worked examples

10 q

Solved Examples

Worked · 10
  1. Solved Ex.7.1
    Elements of group 16 generally show lower values of first ionisation enthalpy compared to the elements of corresponding period of group 15. Why ?
  2. Solved Ex.7.2
    The values of first ionisation enthalpy of S and Cl are 1000 and 1256 kJ mol−1^{-1}, respectively. Explain the observed trend.
  3. Solved Ex.7.3
    Why is there a large difference between the melting and boiling points of oxygen and sulfur ?
  4. Solved Ex.7.4
    Fluorine has less negative electron gain affinity than chlorine. Why ?
  5. Solved Ex.7.5
    Bond dissociation enthalpy of F2\mathrm{F_2} (158.8 kJ mol−1^{-1}) is lower than that of Cl2\mathrm{Cl_2} (242.6 kJ mol−1^{-1}) Why ?
  6. Solved Ex.7.6
    Noble gases have very low melting and boiling points. Why ?
  7. Solved Ex.7.7
    Which form of sulfur shows paramagnetic behaviour ?
  8. Solved Ex.7.8
    Dioxygen is paramagnetic inspite of having even number of electrons. Explain.
  9. Solved Ex.7.9
    High concentration of ozone can be dangerously explosive. Explain.
  10. Solved Ex.7.10
    What is the action of concentrated H2SO4\mathrm{H_2SO_4} on (a) HBr (b) HI

Exercises

52 q

1. Select appropriate answers for the following.

Practice · 14
  1. Select appropriate answers for the following.
    Ex Q.1 (i)
    Which of the following has highest electron gain enthalpy ?
    1. A.
      Fluorine
    2. B.
      Chlorine
    3. C.
      Bromine
    4. D.
      Iodine
  2. Ex Q.1 (ii)
    Hydrides of group 16 are weakly acidic. The correct order of acidity is
    1. A.
      H2O>H2S>H2Se>H2Te\mathrm{H_2O > H_2S > H_2Se > H_2Te}
    2. B.
      H2Te>H2O>H2S>H2Se\mathrm{H_2Te > H_2O > H_2S > H_2Se}
    3. C.
      H2Te>H2Se>H2S>H2O\mathrm{H_2Te > H_2Se > H_2S > H_2O}
    4. D.
      H2Te>H2Se>H2O>H2S\mathrm{H_2Te > H_2Se > H_2O > H_2S}
  3. Ex Q.1 (iii)
    Which of the following element does not show oxidation state of +4 ?
    1. A.
      O
    2. B.
      S
    3. C.
      Se
    4. D.
      Te
  4. Ex Q.1 (iv)
    HI acid when heated with conc. H2SO4\mathrm{H_2SO_4} forms
    1. A.
      HIO3\mathrm{HIO_3}
    2. B.
      KIO3\mathrm{KIO_3}
    3. C.
      I2\mathrm{I_2}
    4. D.
      KI
  5. Ex Q.1 (v)
    Ozone layer is depleted by
    1. A.
      NO
    2. B.
      NO2\mathrm{NO_2}
    3. C.
      NO3\mathrm{NO_3}
    4. D.
      N2O5\mathrm{N_2O_5}
  6. Ex Q.1 (vi)
    Which of the following occurs in liquid state at room temperature ?
    1. A.
      HIO3\mathrm{HIO_3}
    2. B.
      HBr
    3. C.
      HCl
    4. D.
      HF
  7. Ex Q.1 (vii)
    In pyrosulfurous acid oxidation state of sulfur is
    1. A.
      Only +2
    2. B.
      Only +4
    3. C.
      +2 and +6
    4. D.
      Only +6
  8. Ex Q.1 (viii)
    Stability of interhalogen compounds follows the order
    1. A.
      BrF > IBr > ICl > ClF > BrCl
    2. B.
      IBr > BeF > ICl > ClF > BrCl
    3. C.
      ClF > ICl > IBr > BrCl > BrF
    4. D.
      ICl > ClF > BrCl > IBr > BrF
  9. Ex Q.1 (ix)
    BrCl reacts with water to form
    1. A.
      HBr
    2. B.
      Br2+Cl2\mathrm{Br_2 + Cl_2}
    3. C.
      HOBr
    4. D.
      HOBr + HCl
  10. Ex Q.1 (x)
    Chlorine reacts with excess of fluorine to form.
    1. A.
      ClF
    2. B.
      ClF3\mathrm{ClF_3}
    3. C.
      ClF2\mathrm{ClF_2}
    4. D.
      Cl2F3\mathrm{Cl_2F_3}
  11. Ex Q.1 (xi)
    In interhalogen compounds, which of the following halogens is never the central atom.
    1. A.
      I
    2. B.
      Cl
    3. C.
      Br
    4. D.
      F
  12. Ex Q.1 (xii)
    Which of the following has one lone pair of electrons ?
    1. A.
      IF3\mathrm{IF_3}
    2. B.
      ICl
    3. C.
      IF5\mathrm{IF_5}
    4. D.
      ClF3\mathrm{ClF_3}
  13. Ex Q.1 (xiii)
    In which of the following pairs, molecules are paired with their correct shapes ?
    1. A.
      [I3]\mathrm{[I_3]} : bent
    2. B.
      BrF5\mathrm{BrF_5} : trigonal bipyramid
    3. C.
      ClF3\mathrm{ClF_3} : trigonal planar
    4. D.
      [BrF4]\mathrm{[BrF_4]} : square planar
  14. Ex Q.1 (xiv)
    Among the known interhalogen compounds, the maximum number of atoms is
    1. A.
      3
    2. B.
      6
    3. C.
      7
    4. D.
      8

2. Answer the following.

Practice · 14
  1. Answer the following.
    Ex Q.2 (i)
    Write the order of the thermal stability of the hydrides of group 16 elements.
  2. Ex Q.2 (ii)
    What is the oxidation state of Te in TeO3\mathrm{TeO_3} ?
  3. Ex Q.2 (iii)
    Name two gases which deplete ozone layer.
  4. Ex Q.2 (iv)
    Give two uses of ClO2\mathrm{ClO_2}
  5. Ex Q.2 (v)
    What is the action of bromine on magnesium metal ?
  6. Ex Q.2 (vi)
    Write the names of allotropic forms of selenium.
  7. Ex Q.2 (vii)
    What is the oxidation state of S in H2SO4\mathrm{H_2SO_4}.
  8. Ex Q.2 (viii)
    The pKa\mathrm{pK_a} values of HCl is -7.0 and that of HI is -10.0. Which is the stronger acid ?
  9. Ex Q.2 (ix)
    Give one example showing reducing property of ozone.
  10. Ex Q.2 (x)
    Write the reaction of conc. H2SO4\mathrm{H_2SO_4} with sugar.
  11. Ex Q.2 (xi)
    Give two uses of chlorine.
  12. Ex Q.2 (xii)
    Complete the following. 1. ICl3+H2O⟶\mathrm{ICl_3} + \mathrm{H_2O} \longrightarrow ........ + ...... + ICl\mathrm{ICl} 2. I2+KClO3⟶\mathrm{I_2} + \mathrm{KClO_3} \longrightarrow ....... + KIO2\mathrm{KIO_2} 3. BrCl+H2O⟶\mathrm{BrCl} + \mathrm{H_2O} \longrightarrow ....... + HCl 4. Cl2+ClF3⟶\mathrm{Cl_2} + \mathrm{ClF_3} \longrightarrow ........ 5. H2C=CH2+ICl⟶\mathrm{H_2C{=}CH_2} + \mathrm{ICl} \longrightarrow ....... 6. XeF4+SiO2⟶\mathrm{XeF_4} + \mathrm{SiO_2} \longrightarrow ....... + SiF4\mathrm{SiF_4} 7. XeF6+6H2O⟶\mathrm{XeF_6} + 6\mathrm{H_2O} \longrightarrow ........ + HF 8. XeOF4+H2O⟶\mathrm{XeOF_4} + \mathrm{H_2O} \longrightarrow ....... + HF
  13. Ex Q.2 (xiii)
    Match the following
    AB
    XeOF2\mathrm{XeOF_2}Xenon trioxydifluoride
    XeO2F2\mathrm{XeO_2F_2}Xenon monooxydifluoride
    XeO3F2\mathrm{XeO_3F_2}Xenon dioxytetrafluoride
    XeO2F4\mathrm{XeO_2F_4}Xenon dioxydifluoride
  14. Ex Q.2 (xiv)
    What is the oxidation state of xenon in the following compounds. XeOF4\mathrm{XeOF_4}, XeO3\mathrm{XeO_3}, XeF6\mathrm{XeF_6}, XeF4\mathrm{XeF_4}, XeF2\mathrm{XeF_2}.

3. Answer the following.

Practice · 20
  1. Answer the following.
    Ex Q.3 (i)
    The first ionisation enthalpies of S, Cl and Ar are 1000, 1256 and 1520 kJ/mol−1^{-1}, respectively. Explain the observed trend.
  2. Ex Q.3 (ii)
    "Acidic character of hydrides of group 16 elements increases from H2O\mathrm{H_2O} to H2Te\mathrm{H_2Te}" Explain.
  3. Ex Q.3 (iii)
    How is dioxygen prepared in laboratory from KClO3\mathrm{KClO_3} ?
  4. Ex Q.3 (iv)
    What happens when a. Lead sulfide reacts with ozone (O3)(\mathrm{O_3}). b. Nitric oxide reacts with ozone.
  5. Ex Q.3 (v)
    Give two chemical reactions to explain oxidizing property of concentrated H2SO4\mathrm{H_2SO_4}.
  6. Ex Q.3 (vi)
    Discuss the structure of sulfure dioxide.
  7. Ex Q.3 (vii)
    Fluorine shows only -1 oxidation state while other halogens show -1, +1, +3, +5 and +7 oxidation states. Explain.
  8. Ex Q.3 (viii)
    What is the action of chlorine on the following a. Fe b. Excess of NH3\mathrm{NH_3}
  9. Ex Q.3 (ix)
    How is hydrogen chloride prepared from sodium chloride ?
  10. Ex Q.3 (x)
    Draw structures of XeF6\mathrm{XeF_6}, XeO3\mathrm{XeO_3}, XeOF4\mathrm{XeOF_4}, XeF2\mathrm{XeF_2}.
  11. Ex Q.3 (xi)
    What are inter-halogen compounds ? Give two examples.
  12. Ex Q.3 (xii)
    What is the action of hydrochloric acid on the following ? a. NH3\mathrm{NH_3} b. Na2CO3\mathrm{Na_2CO_3}
  13. Ex Q.3 (xiii)
    Give two uses of HCl.
  14. Ex Q.3 (xiv)
    Write the names and structural formulae of oxoacids of chlorine.
  15. Ex Q.3 (xv)
    What happens when a. Cl2\mathrm{Cl_2} reacts with F2\mathrm{F_2} in equal volume at 437 K. b. Br2\mathrm{Br_2} reacts with excess of F2\mathrm{F_2}.
  16. Ex Q.3 (xvi)
    How are xenon fluorides XeF2\mathrm{XeF_2}, XeF4\mathrm{XeF_4} and XeF6\mathrm{XeF_6} obtained ? Give suitable reactions.
  17. Ex Q.3 (xvii)
    How are XeO3\mathrm{XeO_3} and XeOF4\mathrm{XeOF_4} prepared ?
  18. Ex Q.3 (xviii)
    Give two uses of neon and argon.
  19. Ex Q.3 (xix)
    Describe the structure of Ozone. Give two uses of ozone.
  20. Ex Q.3 (xx)
    Explain the trend in following atomic properties of group 16 elements. i. Atomic radii ii. Ionisation enthalpy iii. Electronegativity.

4. Answer the following.

Practice · 4
  1. Answer the following.
    Ex Q.4 (i)
    Distinguish between rhombic sulfur and monoclinic sulfur.
  2. Ex Q.4 (ii)
    Give two reactions showing oxidising property of concentrated H2SO4\mathrm{H_2SO_4}.
  3. Ex Q.4 (iii)
    How is SO2\mathrm{SO_2} prepared in laboratory from sodium sulfite? Give two physical properties of SO2\mathrm{SO_2}.
  4. Ex Q.4 (iv)
    Describe the manufacturing of H2SO4\mathrm{H_2SO_4} by contact process.