Paramagnetic character is shown by those atoms or molecules which have unpaired electrons. In the given compounds $$CO$$ is not paramagnetic since, it does not have unpaired electrons. The configuration of $$CO$$ molecule is
$$CO\left( {14} \right) = \sigma 1{s^2},\mathop \sigma \limits^* 1{s^2},\sigma 2{s^2},$$ $$\mathop \sigma \limits^* 2{s^2},\sigma 2p_x^2,\pi 2p_y^2 \approx \pi 2p_z^2$$
182.
Which of the following contains both covalent and ionic bond?
Paramagnetic species contains unpaired electrons in their molecular orbital electronic configuration.
Molecular orbital configuration of the given species is as
$$CO\left( {6 + 8 = 14} \right)$$
$$ = \sigma 1{s^2},\mathop \sigma \limits^* 1{s^2},\sigma 2{s^2},\mathop \sigma \limits^* 2{s^2},$$ $$\pi 2p_x^2 \approx \pi 2p_y^2,\sigma 2p_z^2$$
( All the electrons are paired so, it is diamagnetic ).
$$O_2^ - \left( {8 + 8 + 1 = 17} \right)$$
$$ = \sigma 1{s^2},\mathop \sigma \limits^* 1{s^2},\sigma 2{s^2},\mathop \sigma \limits^* 2{s^2},$$ $$\sigma 2p_z^2,\pi 2p_x^2 \approx \pi 2p_y^2,\mathop \pi \limits^* 2p_x^2 \approx \mathop \pi \limits^* 2p_y^1$$
( It contains one unpaired electron so, it is paramagnetic. )
$$C{N^ - }\left( {6 + 7 + 1 = 14} \right) = {\text{same}}\,{\text{as}}\,CO$$
$$N{O^ + }\left( {7 + 8 - 1 = 14} \right) = {\text{same}}\,{\text{as}}\,CO$$
Thus, among the given species only $$O_2^ - $$ is paramagnetic.
185.
In which of the following molecule/ion all the bonds are not equal?
In $${C_2}{H_2},C$$ undergoes, $$sp$$ hybridisation.
Ground state :
Excited state :
In $$S{F_6},S$$ undergoes $$s{p^3}{d^2}$$ hybridisation.
Ground state :
Excited state :
In $$S{O_2},S$$ undergoes $$s{p^2}$$ hybridisation.
In $$I{F_7},I$$ undergoes $$s{p^3}{d^3}$$ hybridisation.
Ground state :
Excited state :
188.
Which one of the following molecules contain no $$\pi {\text{ - bond?}}$$
All the molecules have $$O$$ - atom with lone pairs, but in $${H_2}O$$ the $$H $$ - atom has no vacant orbital for $$\pi $$ - bonding. That's why it does not have any $$\pi $$ - bond.
In all other given molecules, the central atom because of the presence of vacant orbitals is capable to form $$\pi $$ - bonds.
189.
$$C{F_4},S{F_4}$$ and $$Xe{F_4}$$ contain the following electronic structures on their central atoms. Which one is correct option?
A
1, 2 and 3 lone pairs of electrons respectively
B
0, 1 and 2 lone pairs of electrons respectively
C
1, 1 and 1 lone pairs of electrons respectively
D
No lone pairs of electrons on any molecule
Answer :
0, 1 and 2 lone pairs of electrons respectively
$$C{F_4} - s{p^3},$$ tetrahedral but no unpaired electron.
$$S{F_4} - s{p^3}d,$$ trigonal bipyramidal with one unpaired electron.
$$Xe{F_4} - s{p^3}{d^2},$$ square planar, two lone pairs of electrons.
190.
The correct order of bond angles (smallest first) in $${H_2}S,\,N{H_3},B{F_3}\,{\text{and}}\,Si{H_4}$$ is