In which of the folllowing transformations, the bond order has increased and the magnetic behaviour has changed?

(a) ${\mathrm{C}}_2^{+}\to {\mathrm{C}}_2$                      (b) ${\mathrm{NO}}^{+}\to \mathrm{NO}$

(c) ${\mathrm{O}}_2\to {\mathrm{O}}_2^{+}$                       (d) ${\mathrm{N}}_2\to {\mathrm{N}}_2^{+}$

The bond having the highest bond energy is :

(1) C=C 

(2) C=S

(3) C=O

(4) P=N

H.O.M.O. (Highest Occupied Molecular Orbital) of CO molecular is :

(1) Non-bonding M.O. with slight antibonding character

(2) Non-bonding M.O. with slight bonding character

(3) Pure non-bonding M.O.

(4) None of the above

An incorrect match among the following is:

In which of the following species central atom is NOT surrounded by exactly 8 valence electrons?

(1) $B{F_4}^{-}$

(2) $NC{l}_3$

(3) $PC{l_4}^{+}$

(4) $S{F}_4$

The structure of ${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6$ is as follows :

How many derivative structures of ${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_4{\mathrm{X}}_2$ can be derived from the basic structure, by the

replacement of two hydrogen atoms?

(a) 2                                         (b) 3

(c) 4                                         (d) 5    

Correctly match is :

(1) ${\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2}$ atomic orbital                                    $—$One nodal plane 

(2) $P_y$ atomic orbital                                          $—$Two nodal plane 

(3) ${\sigma }_{px}$                                                              $—\psi$ (gerade)

(4) ${\pi }_{py}$                                                              $—\psi$ (ungerade)

In which of the following molecular shape $d_{z^{2-}}$ orbital must not be involved in bonding?

(1) Pentagonal planar 

(2) Trigonal planar 

(3) Linear 

(4) Square planar

Consider the following reaction:

${\mathrm{MX}}_4+\mathrm{X}{\text{'}}_2\to {\mathrm{MX}}_4\mathrm{X}{\text{'}}_2$

If atomic number of M is 52 and X and X' are halogens and X' is more electronegative than X.

Then choose correct statement regarding given information:

(a) Both X' atoms occupy axial positions which are formed by overlapping of p and d-orbitals only

(b) All $\mathrm{M}—\mathrm{X} \mathrm{bond} \mathrm{lengths} \mathrm{are} \mathrm{identical} \mathrm{in} \mathrm{both} {\mathrm{MX}}_4 \mathrm{and} {\mathrm{MX}}_4\mathrm{X}{\text{'}}_2 \mathrm{compounds}$

(c) Central atom 'M' does not use anyone valence non-axial set of d-orbital in hybridization of final product

(d) Hybridization of central atom 'M' remains same in both reactant and final product.

Which atom can have more than eight valence electrons when it is forming covalent bond?

1. H

2. N

3. F

4. Cl