Chemical Bonding & Molecular Structure — Page 10 | NEET Chemistry

Q91

Which species does not exhibit paramagnetism?

A N 2 +

B O 2

-

C CO

D NO

Correct Answer

Option C

Solution

Those species which have unpaired electrons are called paramagnetic species.

And those species which have no unpaired electrons are called diamagnetic species.

(A) N 2 + has 13 electrons.

Moleculer orbital configuration of N 2 + =

{\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}}

Here 1 unpaired electrons present, so it is paramagnetic. (B) Molecular orbital configuration of

O_2^ -

(17 electrons) is

{\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}}\,\pi _{2p_x^2}^ * \, = \,\pi _{2p_y^1}^ *

Here 1 unpaired electrons present, so it is paramagnetic.

(A) CO has 14 electrons.

Moleculer orbital configuration of CO =

{\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}}

Here 0 unpaired electrons present, so it is diamagnetic. (D) Molecular orbital configuration of NO (15 electrons) is

{\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}}\,\pi _{2p_x^1}^ * \, = \,\pi _{2p_y^o}^ *

Here 1 unpaired electrons present, so it is paramagnetic.

Q92

d

\pi

-

p

\pi

bond present in

A CO 3 2

-

B PO 4 3-

C NO 3

-

D NO 2

-

Correct Answer

Option B

Solution

In PO 4 3– , P atom has vacant d-orbitals, thus it can form p $\pi$ - d $\pi$ bond.

‘N’ and ‘C’ have no vacant ‘d’ orbital in their valence shell, so they cannot form such bond.

Q93

Which compound has planar structure?

A XeF 4

B XeOF 2

C XeO 2 F 2

D XeO 4

Correct Answer

Option A

Solution

XeF 4 is sp 3 d 2 hybridised and it is square planar :

Q94

Which of the following pairs of compounds is isostructural ?

A Tel 2 , XeF 2

B IBr 2

-

, XeF 2

C IF 3 , XeF 2

D BeCl 2 , XeF 2

Correct Answer

Option B

Solution

<table class=tg> <tbody><tr> <th class=tg-hgcj>Species</th> <th class=tg-hgcj>No. of electrons</th> <th class=tg-hgcj>Structure</th> </tr> <tr> <td class=tg-s6z2>TeI<sub>2</sub></td> <td class=tg-s6z2>158</td> <td class=tg-s6z2>Bent</td> </tr> <tr> <td class=tg-s6z2>XeF<sub>2</sub></td> <td class=tg-s6z2>72</td> <td class=tg-s6z2>Linear</td> </tr> <tr> <td class=tg-baqh>IBr<sub>2</sub></td> <td class=tg-baqh>124</td> <td class=tg-baqh>Linear</td> </tr> <tr> <td class=tg-baqh>XeF<sub>2</sub></td> <td class=tg-baqh>72</td> <td class=tg-baqh>Linear</td> </tr> <tr> <td class=tg-baqh>IF<sub>3</sub></td> <td class=tg-baqh>80</td> <td class=tg-baqh>T-shaped</td> </tr> <tr> <td class=tg-baqh>XeF<sub>3</sub></td> <td class=tg-baqh>72</td> <td class=tg-baqh>Linear</td> </tr> <tr> <td class=tg-baqh>BeCl<sub>2</sub></td> <td class=tg-baqh>38</td> <td class=tg-baqh>Linear</td> </tr> <tr> <td class=tg-baqh>XeF<sub>2</sub></td> <td class=tg-baqh>72</td> <td class=tg-baqh>Linear</td> </tr> </tbody></table>

Q95

Which of the following pairs of ions is isoelectronic and isostructural ?

A

C{O_3}^{2 - },\,\,N{O_3}^ -

B

C{lO_3}^{2 - },\,\,C{O_3}^{2 - }

C

S{O_3}^{2 - },\,\,N{O_3}^ -

D

Cl{O_3}^ - ,\,\,S{O_3}^{2 - }

Correct Answer

Option A

Solution

CO^{2-}_3

; 6 + 24 + 2 = 32; sp 2 ; trigonal planar

N_3^-

: 7 + 24 + 1 = 32; sp 2 , trigonal planar So, these are isoelectronic as well as isostructural.