1

### NEET 2013 (Karnataka)

In which of the following ionization processes the bond energy increases and the magnetic behaviour changes from paramagnetic to diamagnetic.
A
O2 $\to$ O2+
B
C2 $\to$ C2+
C
NO $\to$ NO+
D
N2 $\to$ N2+

## Explanation

Molecular orbital configuration of

O2+ $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_z^2\pi 2p_y^2{\pi ^*}2p_x^1{\pi ^*}2p_y^1$ $\Rightarrow$ Paramagnetic

Bond order = ${{10 - 5} \over 2} = 2.5$

C2 $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_z^2\pi 2p_y^2$ $\Rightarrow$ Diamagnetic

Bond order = ${{8 - 4} \over 2} = 2$

C2+ $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_z^2\pi 2p_y^1$ $\Rightarrow$ Paramagnetic

Bond order = ${{7 - 4} \over 2} = 1.5$

NO $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_z^2\pi 2p_y^2{\pi ^*}2p_x^1$ $\Rightarrow$ Paramagnetic

Bond order = ${{10 - 5} \over 2} = 2.5$

NO+ $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_z^2\pi 2p_x^2\pi 2p_y^2$ $\Rightarrow$ Diamagnetic

Bond order = ${{10 - 4} \over 2} = 3$

N2 $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\pi 2p_x^2\pi 2p_y^2\sigma 2p_z^2$ $\Rightarrow$ Paramagnetic

Bond order = ${{10 - 4} \over 2} = 3$

N2+ $\Rightarrow$ $\sigma 1{s^2}{\sigma ^*}1{s^2}\sigma 2{s^2}{\sigma ^*}2{s^2}\pi 2p_x^2\pi 2p_y^2\sigma 2p_z^1$ $\Rightarrow$ Paramagnetic

Bond order = ${{9 - 4} \over 2} = 2.5$
2

### NEET 2013 (Karnataka)

The outer orbitals of C in ethane molecule can be considered to be hybridized to give three equivalent sp2 orbitals. The total number of sigma $\left( \sigma \right)$ and pi $\left( \pi \right)$ bonds in ethane molecule is
A
3 sigma $\left( \sigma \right)$ and 2 pi $\left( \pi \right)$ bonds
B
4 sigma $\left( \sigma \right)$ and 1 pi $\left( \pi \right)$ bonds
C
5 sigma $\left( \sigma \right)$ and 1 pi $\left( \pi \right)$ bonds
D
1 sigma $\left( \sigma \right)$ and 2 pi $\left( \pi \right)$ bonds

## Explanation

3

### NEET 2013 (Karnataka)

In which of the following pair both the species have sp3 hybridization ?
A
SiF4, BeH2
B
NF3, H2O
C
NF3, BF3
D
H2S, BF3

## Explanation

NF3 and H2O are sp3-hybridisation
4

### NEET 2013

Which of the following is paramagnetic?
A
CN$-$
B
NO+
C
CO
D
O2$-$

## Explanation

$O_2^-$ superoxide has one unpaired electron.