Question 1

Intramolecular hydrogen bonding is found in

Accepted Answer

In o-nitrophenol, hydrogen of O - H group and oxygen of nitro group form intramolecular hydrogen bonding producing a six membered ring structure while in m-nitrophenol, p-nitrophenol and phenol, intermolecular hydrogen bonding are present. The structure is,

Question 2

The hybridisation scheme for the central atom includes a d-orbital contribution in

Accepted Answer

I _3^ - is linear with central iodine atom undergoing s p^3 d-hybridisation and three lone pairs occupying equatorial position. Thus, this structure include d-orbital contribution to the hybridisation scheme. The structure is, PCl _3 structure is s p^3-hybridised with one lone pair. NO _3^ - is s p^2-hybridised and H _2 Se is s p^3 - hybridised with two lone pairs of Se atom.

Question 3

In the following species, how many species have same magnetic moment? (i) Cr ^ 2+ (ii) Mn ^ 3+ (iii) Ni ^ 3+ (iv) Sc ^ 2+ (v) Zn ^ 2+ (vi) V ^ 3+ (vii) Ti ^ +

Accepted Answer

Among the given species, Cr ^ 2+ and Mn ^ 3+ have same number of unpaired electrons. aligned & Unpaired electrons, n=4 \ & Magnetic moment, aligned & = n(n+2) = 4(4+2) \ & = 24 BM aligned aligned

Question 4

The spin only magnetic moment of Fe ^ 3+ ion (in BM) is approximately.

Accepted Answer

Electronic configuration of Fe . aligned _ 26 Fe & =[ Ar ] 3 d^6 4 s^2 \ Fe ^ 3+ & =[ Ar ] 3 d^5 aligned Number of unpaired electrons, n=5 Spin only magnetic moment, _s= n(n+2) BM gathered _s= 5(5+2) \ _s= 35 \ _s=5.85 BM or _s 6 BM gathered

Question 5

Which one of the following compounds is having maximum 'lone pair-lone pair' electron repulsions?

Accepted Answer

XeF _2 has three lone pairs and two bond pairs. The three lone pairs are arranged in the equatorial positions because of which they face maximum repulsion from each other.

Question 6

Identify the species having one -bond and maximum number of canonical forms from the following:

Accepted Answer

Answer option index: 3

Question 7

sp ^3 ~d ^2 hybridisation is not displayed by :

Accepted Answer

Answer option index: 3

Question 8

Energy required to completely separate one mole of a solid ionic compound into gaseous. constituent ions is called

Accepted Answer

Frenkel defect is due to dislocation of ion from its usual lattice site to interstitial position.

Question 9

Which of the following pairs will form the most stable ionic bond?

Accepted Answer

The stability of the ionic bond depends upon the lattice energy which is expected to be more between Mg and F due to +2 charge on Mg atom.

Question 10

OF and F _2 can be compared in terms of

Accepted Answer

This is one unpaired electron in ( O - F ), hence paramagnetic, thus (a) is correct. As bond order of O - F > F - F thus, bond energy of O - F > F - F . Hence, (a) and (b) both are correct.

Question 11

In which pair or pairs is the stronger bond found in the first species? I. O _2^ 2- , O _2; II. N _2, ~N _2^ + III. NO ^ + , NO ^ -

Accepted Answer

Larger the bond order, stronger the bond formed.

Question 12

In the molecules CH _4, NF _3, NH _4^ + and H _2 O

Accepted Answer

CH _4 ; bp =4 ; s p^3-hybridisation NF _3 ; bp =3 ; l p=1 ; s p^3-hybridisation NH _4^ + ; bp =4 ; l p=0 ; s p^3-hybridisation H _2 O ; bp =2 ; l p=2 ; s p^3-hybridisation Hence, all have the same slope.

Question 13

Which one of the following ions has the maximum magnetic moment?

Accepted Answer

Fe ^ 3+ (d^ 5 ) has 5 unpaired electrons therefore magneticmoment = n(n+2) = 5(5+2) =5.91 which is maximum among given options. As Sc ^ 3+ , Ti ^ 3+ , Cr ^ 3+ and V ^ 3+ contain 0,1,3, and 2 number of unpaired electrons respectively.

Question 14

Which of the following represents the correct order of Cl - O bond lengths in ClO ^ - , ClO _ 2 ^ - , ClO _ 3 ^ - , ClO _ 4 ^ - ?

Accepted Answer

The b.o in Cl - O ^ - is 1 The b.o in O = Cl - O ^ - is 1.5 The b.o. in O = Cl = O is 5 3 =1.66 The b.o. in O = O O \| l - O ^ - is 7 4 =1.75 The bond length increases as b.o. decreases.

Question 15

Which of the following has the highest p -p bonding tendency?

Accepted Answer

Nitrogen due to small size is able to show p -p lateral overlap forming N N , rest elements due to bigger size are not able to show p -p lateral overlap.

Question 16

Which of the following does not contain any coordinate bond?

Accepted Answer

HF _ 2 is the only compound among the given options which does not contain any coordinate bond because it has hydrogen bonding. [ H - F H ]^ -

Question 17

Which of the following set contains species having same angle around the central atom?

Accepted Answer

BF _ 3 , BCl _ 3 , BBr _ 3 are s p^ 2 hybridised. So, all have same structure and bond angle i.e. 120^ .

Question 18

In XeF _ 2 , XeF _ 4 , XeF _ 6 the number of lone pairs on Xe are respectively

Accepted Answer

Answer option index: 3

Question 19

Which one of the following molecules will form a linear polymeric structure due to hydrogen bonding?

Accepted Answer

HF form linear polymeric structure due to hydrogen bonding.

Question 20

In the reaction 2 PCl _ 5 PCl _ 4 ^ + + PCl _ 6 ^ - , the change in hybridisation is from

Accepted Answer

2 PCl _ 5 PCl _ 4 ^ + + PCl _ 6 ^ - s p^ 3 d s p^ 3 s p^ 3 d^ 2

Chemical Bonding and Molecular Structure — Previous Year Questions & Solutions