IISER Chemistry - Chemical Bonding
Exam Duration: 45 Mins Total Questions : 30
Atomic orbitals of carbon in graphite have
- (a)
sp hybridisation
- (b)
sp2 hybridisation
- (c)
sp3 hybridisation
- (d)
dsp2 hybridisation
In graphite each carbon atom is connected only to three other carbon atoms by covalent bond and fourth valency is unsatisfied. Where there is a triple bond it is sp2 hybridised.
Butyne-2 contains
- (a)
sp hybridised carbon atoms only
- (b)
sp3 hybridised carbon atoms only
- (c)
both sp and sp2 hybridised carbon atoms
- (d)
both sp and sp3 hybridised carbon atoms
Butyne-2 has the formula H3C-C\(\equiv\)C-CH3 Where there is a single bond carbon is sp3 hybridised and where there is a triple bond it is sp hybridised.
If a molecule MX3 has zero dipole moment,the sigma bonding orbitals used by M (atomic number < 21) are
- (a)
sp hybrid
- (b)
sp2 hybrid
- (c)
sp3 hybrid
- (d)
dsp2 hybrid
sp2 hybrid
Which molecule has a dipole moment?
- (a)
CCl4
- (b)
C6H6
- (c)
BF3
- (d)
HF
HF
Which of the following molecular species has unpaired electrons?
- (a)
N2
- (b)
F2
- (c)
O2-
- (d)
O22
(c) KK \(\left[ { \sigma 2{ s }^{ 2 } } \right] \left[ { \sigma *2s }^{ 2 } \right] \left[ \sigma 2{ p }_{ z }^{ 2 } \right] \left[ \pi 2{ p }_{ x }^{ 2 } \right] \left[ \pi 2{ p }_{ y }^{ 2 } \right] \left[ { \pi }*2{ p }_{ x }^{ 2 } \right] \left[ { \pi }*2{ p }_{ y }^{ 1 } \right] \)
one unpaired electron
(a) KK \(\left[ { \sigma *2s }^{ 2 } \right] \left[ { \sigma *2s }^{ 2 } \right] \left[ \pi 2{ p }_{ x }^{ 2 } \right] \left[ \pi 2{ p }_{ y }^{ 2 } \right] \left[ \pi 2{ p }_{ z }^{ 2 } \right] \)
No unpaired electron
(b) KK \(\left[ { \sigma { 2s }^{ 2 } } \right] \left[ { \sigma *2s }^{ 2 } \right] \left[ \sigma 2{ p }_{ z }^{ 2 } \right] \left[ \pi 2{ p }_{ x }^{ 2 } \right] \left[ \pi 2{ p }_{ y }^{ 2 } \right] ;\)
No unpaired electron.
(d) KK \(\left[ { \sigma 2{ s }^{ 2 } } \right] \left[ { \sigma *2s }^{ 2 } \right] \left[ \sigma 2{ p }_{ z }^{ 2 } \right] \left[ \pi 2{ p }_{ x }^{ 2 } \right] \left[ \pi 2{ p }_{ y }^{ 2 } \right] \left[ { \pi }*2{ p }_{ x }^{ 2 } \right] \left[ { \pi }*2{ p }_{ y }^{ 2 } \right] \)
No unpaired electron
Which one of the following bonds has the most polar character?
- (a)
C-O
- (b)
C-Br
- (c)
C-F
- (d)
C-S
This is due to maximum electronegativity difference; C has electronegativity 2.5 and F has electronegativity value 4.
Length of hydrogen bond ranges from 2.5\(\mathring { A } \) to
- (a)
2.6 \(\mathring { A } \)
- (b)
2.75 \(\mathring { A } \)
- (c)
3.0 \(\mathring { A } \)
- (d)
3.2 \(\mathring { A } \)
The length of hydrogen bond ranges from \(2.5\mathring { A } -2.75\mathring { A } \)
In the compound of the type O=PX3,the phophorus atom exhibits bonding of the type
- (a)
p\(\pi\)-p\(\pi\)
- (b)
d\(\pi\)-d\(\pi\)
- (c)
p\(\pi\)-d\(\pi\)
- (d)
None
Maximum bond energy exists in
- (a)
CH3OH
- (b)
NH2-NH2
- (c)
CH3CI
- (d)
CH-CH3
C - O, 15 kcal mol-1, N - N, 39 Kcal mol1
C-CI, 78 mol-1, C-C, 81.6 Kcal mol-1
Select the molecule which has only one pi-bond.
- (a)
CH=CH
- (b)
CH2=CH=CHO
- (c)
CH3CH=CH2
- (d)
CH3CH=CHCOOH
Out of the given species, one II-bond is present in propane only. Other species have two \(\pi\) - bonds.
The number of antibonding electron pairs in O22- ion on the basis of MO theory is
- (a)
4
- (b)
3
- (c)
2
- (d)
5
Configuration of \({ O }_{ 2 }^{ 2- }\) ion is
KK\({ \left[ { \sigma 2{ s } } \right] }^{ 2 }{ \left[ { \sigma *2s } \right] }^{ 2 }{ \left[ { \sigma }_{ 2 }{ p }_{ z } \right] }^{ 2 }{ \left[ { \pi 2p }_{ x } \right] }^{ 2 }{ \left[ { \pi 2p }_{ y } \right] }^{ 2 }\)
\({ \left[ { \pi }^{ x }{ 2p }_{ x } \right] }^{ 2 }{ \left[ { \pi }^{ x }{ 2p }_{ y } \right] }^{ 2 }\)
Which of the following pairs contains isostructural species?
- (a)
CH3- and CH3+
- (b)
NH4+ and NH3
- (c)
SO42- and BF4-
- (d)
NH2- and BeF2
The nature of interparticle forces in benzene is :
- (a)
dipole-dipole interation
- (b)
dispersion force
- (c)
ion-dipole interaction
- (d)
H-bonding
According to MOT,the species O2+ possesses :
- (a)
bond order of 2.5
- (b)
three unpaired electrons
- (c)
diamagnetic character
- (d)
stability lower than O2
\({ O }_{ 2 }^{ + }\) has configuration
\({ \sigma 1s }^{ 2 }<{ \sigma }^{ s }{ 1s }^{ 2 }<{ \sigma 2s }^{ 2 }<{ \sigma }^{ x }{ 2s }^{ 2 }<{ \sigma 2p }_{ x }^{ 2 }<{ \pi 2p }_{ y }^{ 2 }={ \pi 2p }_{ z }^{ 2 }<{ \pi }^{ x }{ 2p }_{ y }^{ 1 }={ \pi }^{ x }{ 2p }_{ z }^{ 0 }\)
Bond order = 1/2 (nb - na)
= 1/2 (10 - 5) = 21/2
The octahedral shape is associated with
- (a)
PF5
- (b)
SF4
- (c)
TeF6
- (d)
CIF3
All the other three involve sp3d hybridization at the central atom.
The maximum possible number of hydrogen bonds in which a water molecule can participate is
- (a)
4
- (b)
3
- (c)
2
- (d)
1
Amongst the following molecules the one with the largest distance between the two adjacent carbon atoms is
- (a)
Ethane
- (b)
Ethene
- (c)
Ethyne
- (d)
Benzene
Covalent compounds are soluble in
- (a)
Polar solvents
- (b)
Non-polar solvents
- (c)
Concentrated acids
- (d)
All solvents
Covalent compounds are non-polar, so these are soluble in non-polar solvents. (like dissolves like).
Which of the following bonds has the most polar character?
- (a)
C-O
- (b)
C-Br
- (c)
C-F
- (d)
C-S
The electronegativity difference in C - F bond is highest.
The forces present in the crystals of naphthalene are
- (a)
electrostatic
- (b)
Hydrogen bonding
- (c)
van der Waal
- (d)
None of these
Among the alkaline earth metals the element forming predominantly covalent compound is
- (a)
Be
- (b)
Mg
- (c)
Sr
- (d)
Calcium
Due to greater polarising power.
Two elements have electronegativities of 1.2 and 3.0. Bond formed between them would be
- (a)
Ionic
- (b)
Polar covalent
- (c)
Co-ordinate
- (d)
Metallic
Electronegativity difference is 3. - 1.2 = 1.8. So it is less than 1.9 and the bond polar covalent.
Which of the following contains both covalent and ionic bonds?
- (a)
CCI3
- (b)
NH4CI
- (c)
CaCI2
- (d)
H2O
Ionic bond between \({ NH }_4^{+}\) and CI-ions. Covalent bond \({ NH }_4^{+}\) in itself
In which of the following species in the inter-atomic bond angle 109o28'?
- (a)
NH3;(BF4)-1
- (b)
(NH4)+,BF3
- (c)
NH3,BF4
- (d)
(NH2)-1,BF3
Isostructural species are those which have the same shape and hybridisation. Among the given species identify the isostructural pairs.
- (a)
\({ NF }_{ 3 }\quad and\quad { BF }_{ 3 }\)
- (b)
\({ BF }_{ 4 }^{ - }\quad and\quad { NH }_{ 4 }^{ + }\)
- (c)
\({ BCl }_{ 3 }\quad and\quad { BrCl }_{ 3 }\)
- (d)
\({ NH }_{ 3 }\quad and\quad { NO }_{ 3 }^{ - }\)
(a) NF3 ⇒ 3bp + 1/p ⇒ pyramidal
BF3 ⇒ 3bp + O/p ⇒ trigonal planar
(b) \({ BF }_{ 4 }^{ - }\) ⇒ 4bp + O/p
\({ NH }_{ 4 }^{ + }\) ⇒ 4bp + O/p ⇒ etrahedral
(c) BCI3 ⇒ 3bp + O/p ⇒ trigonal planar
BrCI3 ⇒ 3bp + 2IP ⇒ T-share
(d) NH3 ⇒ 3bp + 1/p ⇒ pyramidal
\({ NO }_{ 3 }^{ - }\) ⇒ 3bp + O/p ⇒ trigonal planar
Which of the following hybridisation is not possible?
- (a)
sp3
- (b)
sp3d3
- (c)
sd3
- (d)
None of the above
sp3 = tetrahedral geometry
sp3d3 = pentagonal bipyramidal geometry
sd3 = it is not possible
Arrange the following in the correct order of bond length: N2, O2 and Cl2 .
- (a)
N2>Cl2>O2
- (b)
N2
2 2 - (c)
N2
2 2 - (d)
Cl2
2 2
Molecule | Bond multiplicity |
---|---|
CI - CI | 1 |
O = O | 2 |
N \(\equiv\) N | 3 |
As bond multiplicity increases, bond length decreases.
Among the following molecules which have trigonal planar structure XeO3, SO3, BF3, NH3 ?
- (a)
XeO3 and BF3
- (b)
BF3 and SO3
- (c)
NH3 and SO3
- (d)
All of the above
\(In\quad { BF }_{ 3 },\quad H=\frac { 3+3 }{ 2 } =3\left( { sp }^{ 2 } \right) :\quad Trigonal\quad planar\\ In\quad S{ O }_{ 3 },\quad H=\frac { 6+0 }{ 2 } =3\left( { sp }^{ 2 } \right) :\quad Trigonal\quad planar\)
Among the following the maximum covalent character is shown by the compound
- (a)
FeCl2
- (b)
SnCl2
- (c)
AlCl3
- (d)
MgCl2
According to Fajan's rule, the polarising power and hence, the covalent character of a molecule depends on
(i) Larger charge on ions
(ii) Smaller size of cation
(iii) Larger size of anion Here, all anions are same i.e., Cl- anion hence, the covalent character will be decided by polarising power of cation.
\({ Fe }^{ 2+ }\quad \quad \quad \quad { Sn }^{ 2+ }\quad \quad \quad \quad \underset { Maximum\quad Charge }{ \overset { { AI }^{ 3+ } }{ \uparrow } } \quad \quad { Mg }^{ 2+ }\)
Out of the above AI3+ has maximum charge and maximum polarising power, hence maximum covalent character.
The hybridisation of orbitals of N atom in NO3-, NO2+ and NH4+ respectively are
- (a)
sp2,sp,sp3
- (b)
sp,sp3,sp2
- (c)
sp2,sp3,sp
- (d)
sp,sp2,sp3
\({ NO }_{ 3 }^{ - }=\frac { 1 }{ 2 } (5+1)=3\Rightarrow { sp }^{ 2 }\) hybridized
\({ NO }_{ 2 }^{ + }=\frac { 1 }{ 2 } (5-1)=2\Rightarrow \)sp hybridized
\({ NH }_{ 4 }^{ + }=\frac { 1 }{ 2 } (5+4-1)=4\Rightarrow \)sp3 hybridized