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Chemical Bonding and Molecular Structure

 

2. The number of types of bonds present between 2 carbon atoms in calcium carbide is
     1) 2σ, 2Π      2) 2σ, 1Π      3) 1σ, 2Π      4) 3σ, 2Π
Ans: (3)

 

3. The number of antibonding electrons present in N2, O2 molecules is
     1) 10, 10      2) 4, 6      3) 6, 4      4) 3, 2
Ans: (2)

 

4. Maximum number of lone pairs associated with Xe among the following molecule is
     1) XeF2      2) XeF4      3) XeF6      4) XeO3
Ans: (1)

 

5. The dipole moment of KCl is 3.336 × 10-29 coulomb metre. The inter ionic distance is
     2.6 × 10-10 m. Percentage of ionic character of KCl is
     1) 20%      2) 80.1%      3) 19.9%      4) 78%
Ans: (2)

 

6. A square planar complex is formed by the hybridisation of the following set of atomic orbitals
     1) s, px, py, pz      2) s, px, py, pz, d     3) d, s, px, py      4) s, px, py, pz, d, d
Ans: (3)
Explanation: In dsp2 hybridization, square planar geometry is resulted. Where dx2 - y2  orbital (inner d sub-shell) is participated.

 

7. Hybridization of the underlined atom changes in

     1)       2)  
     3)       4) in all these cases
Ans: (1)

 

8. Bond angle of 109°28' is found in
     1) NH3      2) H2O      3) ClF3      4) N+H4
Ans: (4)
Explanation: Shape of NH4+ is tetrahedral.
                             Bond angle = 109°28'.

 

9. The pair of molecules having permanent dipole moments is
     1) SiF4, NO2      2) NO2, CO2     3) NO2, O3      4) SiF4, CO2
Ans: (3)
Explanation:
                            
       The dipole moment of molecules having irregular geometry can't be zero.

 

10. The maximum number of 90° angle between bond pair and bond pair of electrons is observed in
     1) sp3d2hybridization      2) sp3d hybridization     
     3) dsp2hybridization      4) sp3d3 hybridization
Ans: (1)
Explanation: e.g.: SF6


               In the plane = four 90° angles
above the plane = one 90° angle
below the plane = one 90° angle.

 

11. Incorrect statement among the following is
     1) Boiling point of o-nitrophenol < p-nitrophenol.
     2) Valence angle between H and y-z bond is always constant.
     3) Hydrogen bonds are linear or slightly bent.
     4) Most of the hydrogen bonds are asymmetric.
Ans: (2)
Explanation: Bond angle between H and y-z bond varies between 100° to 140° .

 

12. The electron probability distribution around a group of nuclei in a molecule is given by a
     1) Hybrid orbital      2) Atomic orbital     3) Molecular orbital      4) all the above
Ans: (3)
Explanation: It is given by molecular orbital only.

 

13. The filling of electrons in molecular orbitals is similar to that of atomic orbitals i.e. in according to
     1) Hund's rule                     2) Pauli's exclusion principle
     3) Aufbau's principle         4) all the above
Ans: (4)
Explanation: As filling of electrons in molecular orbitals is very similar to atomic orbitals by following 3 rules.

 

14. The formal charge on central atom and surrounded atoms in Ozone is
     1) +1, 0, -1      2) +1, 0, +1      3) +1, +1, 0      4) +1, +1, +1
Ans: (1)
Explanation:


Formal charge on central 'O' = 6 - 2 - 3 = 1
2nd oxygen = 6 - 4 - 2 = 0
3rd oxygen = 6 - 6 - 1 = -1.

 

15. Pauling's emperical equation to calculate covalent radius is dAB = rA + rB + C(xA - xB). Where C value for bonds involving atoms of 2nd period is
     1) 0.02      2) 0.08      3) 0.06      4) 0.06 or 0.08
Ans: (2)
Explanation: "C" value for 2nd period elements = 0.08

 

16. Correct order of covalent bond lengths of C = O, N = O, C = N, C = C is
     1) C = N > C = C > C = O > N = O
     2) C = N > N = O > C = C > C = O
     3) C = N > C = C > N = O > C = O
     4) C = C > C = N > N = O > C = O
Ans: (3)
Explanation: Bond lengths: C = N = 138 pm, C = C = 133 pm, 
                                         N = O = 122 pm, C = O = 121 pm.

 

17. Experimentlly determined bond length in O3 is
     1) 148 pm for single bond, 121 pm for double bond
     2) 121 pm for single bond, 148 pm for double bond
     3) 148 pm for single bond, 148 pm for double bond
     4) 128 pm for both the bonds
Ans: (4)
Explanation: O
                              
                  Due to resonance both the bond lengths are same.

 

18. Correct order to dipole moments of HF, H2O, NH3 is
     1) HF > H2O > NH3            2) H2O > HF > NH3
     3) NH3 > HF > H2O           4) NH3 > H2O > HF
Ans: (1)
Explanation: Dipole moments of HF = 1.78 D, H2O = 1.85 D, NH3 = 1.47 D.

 

19. ClF3 belongs to the molecular type
        1) AB3             2) AB3E2               3) AB2E             4) AB3E
Ans: (2)
Explanation:
                              
           A = Cl, B = F, E = no. of lone pairs = 2.

20. Identify the correct set:
  
 
Ans: (3)
Explanation: XeF4 - sp3d2 - square planar - 2 L.P.S.
                       ClF3 - sp3d - T shape - 2 L.P.S.
                        SF4 - sp3d - see-saw - 1 L.P.

 

21. In which of the following pairs of molecules/ ions both the species are not likely to exist?
    
Ans: (1)

 

22. In which of the following pairs of the two species are not iso structural?
     1)           2)          3)                   4) 
Ans: (2)

 

23. Compound having maximum covalent character among the following is
        1) MgCl2               2) FeCl2               3) AlCl3                 4) SnCl2
Ans: (3)
Explanation: According to Fajan's rule compound having smallest cation size (Al+3), maximum charge (+3) has maximum polarising power and is more covalent.

 

24. In which of the following process, the bond order has increased and the magnetic behaviour has changed?
     1) C2   C2+         2) NO  NO+        3) O2  O2+        4) N2  N2+
Ans: (2)

 

25. Lattice energy of an ionic compound depends upon
        1) charge on the ion and size of the ion     2) packing of ions
        3) size of the ions                                      4) charge on the ion only
Ans: (4)
Explanation:

Posted Date : 15-10-2020

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