HYBRIDIZATION & MOT....Q&A

Q1 What is hybridization?
Ans: The process of intermixing of atomic orbitals of slightly different energies of same atom to get
same number of new orbitals of equivalent energies and shape is called hybridization
Q2 Which hybrid orbital are used by carbon atoms in the following molecules (L-II)
(a) CH3CH2OH b) CH3COOH .            
Ans a)sp
3
,sp
3
b)sp
3
sp
2
Q3. Give an example for sp
2
and sp
3
hybrid molecules also give their shape.
Ans sp
2
-Trigonal planar e.g, BH3
sp
3
- Tetrahadral eg CH4
Q4 . Draw the shapes of following hybrid orbitals. sp, sp
2
(L_II)
B
Ans sp B A B sp
2
B  A
B
Q5. Draw the shapes of H2O and CH4 molecule.

Q6 Arrange the following orbitals in the increasing order of s- character: sp, sp
2
, sp
3
(L-I)
Ans. sp
3
< sp
2
<sp
Q7 How is paramagnetic character of a compound is related to the no. of unpaired electrons?
Ans. Greater the number of unpaired electrons greater will be the paramagnetic character
Q3 . Calculate bond order of N2 ? (L-II)
Ans. 3
Q8 Give electronic configuration for C2?
Ans.
1s
2
*1s
2
2s
2
*2s
2
2py
2
2pz

Q9 Calculate the number of unpaired electrons in the B2 molecule.
Ans 2

Q10 Define bond order and give the relationship between bond order and bond length .
Ans Bond order (b.o.) is defined as one half the difference between the number of electrons present
in the bonding and the antibonding orbitals i.e., Bond order (b.o.) = ½ (Nb–Na)
Bond order is inversely proportional to bond length

Q11 Explain the shape of NH3 molecule using hybridization.

Q12 Arrange the following in order of decreasing bond angles.
i)  CH4, NH3, H2O, BF3, C2H2
ii)  NH3, NH2
-,NH4
+
Ans (i)C2H2(180) > BF3(120)>CH4 (109.28)>NH3(107) > H2O(104.5)
(ii)NH4
+
> NH3  >NH2
-,

Q13 Compare the relative stability of following species and indicate their magnetic properties .
O2, O2
+
O2

Ans. Stability increases as O2
-< O2, <O2
+
Bond order 1
1
2
� ,2, 2
1
2
�
Magnetic properties -Paramagnetic


Q15 Show the non-existence of helium molecule based on molecular orbital theory.
Ans Helium molecule (He2 ): The electronic configuration of helium atom is 1s2. Each helium atom
contains 2 electrons, therefore, in He2 molecule there would be 4 electrons. These electrons will be
accommodated in σ1s and σ*1s molecular orbitals leading to electronic configuration: He2 : (σ1s)
2
(σ*1s)
2
.Bond order of He
2
is ½(2 – 2) = 0. He2 molecule is therefore unstable and does not exist.
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