Limitations of VBT

Q.

Briefly explain why is sigma bond stronger than pi bond?

Q. Giving justification, categorise the following molecules/ions as nucleophile or electrophile:

$H{S}^{-},B{F}_3,C_2{H}_5{O}^{-}$
$(C{H}_3{)}_{3}N:,\stackrel{+}{Cl}$
$C{H}_3-\stackrel{+}{C}=O,H_{2}N{:}^{-},\stackrel{+}{N}{O}_2$

Q.

In a covalent solid, lattice points are occupied by

1. atoms

2. ions

3. molecule

4. electrons

Q. Why dose type of overlap given in the following figure not result in bond formation ?

Q. Number of bridging CO ligands in $\left[M{n}_2{\left(CO\right)}_{10}\right]$ is __________ .

Q. Assuming $z-$axis inter nuclear axis. In which of the following orbitals overlap to form $\sigma$ bond.
$p_y+p_z$

Q. Select the incorrect overlap if $z$-axis is the inter-nuclear axis:

1. $2p_y+2p_y\to \pi 2p_y$
2. $2p_z+2p_z\to \sigma 2p_z$
3. $2p_x+2p_x\to \pi 2p_x$
4. $1s+2p_y\to \pi (1s-2p_y)$

Q. A sigma bond is formed by the overlapping of:

1. $s-s$ orbital alone
2. $s$ and $p$ orbital alone
3. $p-p$ orbital along the sides
4. $s-s,s-p$ or $p-p$ orbital along internuclear axis

Q. Which species contain only $\pi -$bond among the following?

1. $O^{2-}$
2. $O_2$
3. $B_2$
4. $C_2^{2-}$

Q. Which of the following depict a $\sigma$-bond?

1. 

2. 

3. 

4. None of these

Q.

Which of the following represents s - s, s - p and p - p overlap respectively?

1. I, II, III

2. III, II, I

3. I, III, II

4. II, III, I

Q.

Which of the following represents s - s, s - p and p - p overlap respectively?

1. I, II, III
2. III, II, I
3. I, III, II
4. II, III, I

Q. Which of the following depict a $\sigma$-bond?

1. 

2. 

3. 

4. None of these

Q. Which of the following depict a $\sigma$-bond?

1. 

2. 

3. 

4. None of these

Q.

Which of the following depict a $\pi$-bond?

1. 

2. 

3. 

4. None of these

Q.

Which of the following depict a $\pi$-bond?

1. None of these

2. 

3. 

4.