Valence Bond Theory

Q. $B{F}_3$ is planar and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are :

1. $s{p}^2\text{and}8$
2. $s{p}^3\text{and}4$
3. $s{p}^3\text{and}6$
4. $s{p}^2\text{and}6$

Q. Gadolinium has a low value of third ionisation enthalpy because of

Q.

$C_2{O}_4^{2-}$ is a weak ligand but acts as a strong ligand in $K_3\left[Co\right(C_2{O}_4{)}_3]$ and induces the pairing of electrons against Hund's rule. Why?

Q.

Hyperconjugation involves an overlap of which of the following orbitals?

1. $\mathrm{\sigma }-\mathrm{\sigma }$

2. $\mathrm{\sigma }-\mathrm{p}$

3. $\mathrm{p}-\mathrm{p}$

4. $\mathrm{\pi }-\mathrm{\pi }$

Q. The hybridization involved in complex $\left[Ni\right(CN{)}_4{]}^{2-}$ is (Atomic number of Ni = 28)

1. $d^{2}s{p}^2$
2. $d^{2}s{p}^3$
3. $ds{p}^2$
4. $s{p}^3$

Q.

What is a pi-acid ligand?

Q.

The number of $s{p}^3$ hybridised boron atoms in borax are

1. 2

2. 3

3. 4

4. 1

Q. In which of the following pairs, electron gain enthalpies of constituent elements are nearly the same or identical?

$\left(A\right)Rb\text{and}Cs$

$\left(B\right)Na\text{and}K$

$\left(C\right)Ar\text{and}Kr$

$\left(D\right)I\text{and}At$

Choose the correct answer from the options given below:

Q.

Explain the formation of $H_2$ molecule on the basis of valence bond theory.

Q. If radius of second orbit is X then de broglie wavelenghth in 4th orbit is 8 pi x 2pi x 4 pi x 6 pi x

Q. Among the following complex ions, which is diamagnetic in nature is

1. $[Co{F}_6{]}^{3-}$
2. $[NiC{l}_4{]}^{2-}$
3. $[CuC{l}_4{]}^{2-}$
4. $\left[Ni\right(CN{)}_4{]}^{2-}$

Q. In fcc packing if all the atoms through one of the body diagonal plane are missing , the total number of atoms in the unite cell is

Q.

Pick out the correct statement with respect to $\left[Mn\right(CN{)}_6{]}^{3-}$

1. It is $s{p}^3{d}^2$ hybridised and octahedral

2. It is $s{p}^3{d}^2$ hybridised and tetrahedral
   

3. It is $d^{2}s{p}^3$ hybridised and octahedral
   

4. It is $ds{p}^2$ hybridised and square planar

Q. Which one of the following is an inner orbital complex as well as diamagnetic in behaviour?
(Atomic no.:Zn=30, Cr=24, Co=27)

1. $\left[Zn\right(N{H}_3{)}_6{]}^{2+}$
2. $\left[Cr\right(N{H}_3{)}_6{]}^{3+}$
3. $\left[Co\right(N{H}_3{)}_6{]}^{3+}$
4. None of the above

Q.

Why ${\mathrm{AlCl}}_3$ is a Lewis acid?

Q. The type of hybridization of Mn in KMnO4 is

Q.

According to VSEPR theory predict the geometry and shape of I₃⁺ion.

Q.

Why is ${\left[\mathrm{Cr}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}$ a high spin complex?

Q.

The number of $s{p}^2$ hybridised boron atoms in borax are

1. 2

2. 4

3. 3

4. 1

Q. Why does lattice energy decreases with increase in anionic and cationic size?

Q.

Which of the following species is not paramagnetic?

1. ${\mathrm{O}}_2$

2. ${\mathrm{B}}_2$

3. $\mathrm{NO}$

4. $\mathrm{CO}$

Q. The geometry of $\left[Ni\right(CO{)}_4]$ and $[NiC{l}_4{]}^{2-}$ are respectively:

1. Both are tetrahedral
2. Square planar and tetrahedral
3. Both are square planar
4. Tetrahedral and square planar

Q. According to the molecular orbital theory, for $C{O}^{+}$:

1. The bond order is less than that of $CO$ and $C{O}^{+}$ is paramagnetic
2. The bond order is more than that of $CO$ and $C{O}^{+}$ is paramagnetic while $CO$ is diamagnetic
3. The bond order is less than that of CO and $C{O}^{+}$ is diamagnetic
4. The bond order is more than that of CO and $C{O}^{+}$ is diamagnetic while CO is paramagnetic

Q.

Which type of hybridization is found in the ethyne molecule?

Q. The hybridisation of Fe in $[Fe{F}_6{]}^{3-}$ is $s{p}^3{d}^2$, the number of unpaired electrons present is

1. 5
2. 4
3. 2
4. 1

Q. The increasing order of magnetic moment values of the given compounds is:
$\left(I\right)\left[Fe\right(CN{)}_6{]}^{4-}$
$\left(II\right)\left[Fe\right(CN{)}_6{]}^{3-}$
$\left(III\right)\left[Cr\right(N{H}_3{)}_6{]}^{3+}$
$\left(IV\right)\left[Ni\right(H_{2}O{)}_6{]}^{2+}$

1. $II<III<I<IV$
2. $I<II<III<IV$
3. $IV<III<II<I$
4. $I<II<IV<III$

Q.

Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:
$\left[Fe\right(C{N}_6){]}^{4-}$

$[Fe{F}_6{]}^{3-}$

$\left[Co\right(C_2{O}_4{)}_3{]}^{3-}$

$[Co{F}_6{]}^{3-}$

Q.

Using valence bond theory, explain the following in relation to the complexes given below
$\left[Mn\right(CN{)}_6{]}^{3-},\left[Co\right(N{H}_3{)}_6{]}^{3+},\left[Cr\right(H_{2}O{)}_6{]}^{3+},[FeC{l}_6{]}^{4-}$
(a) Type of hybridisation
(b) Inner or outer orbital
(c) Magnetic behaviour
(d) Spin only magnetic moment value.

Q.

Valence bond theory was proposed by________.

Q.

How does the chemical reactivity of halogens vary?