Chemical Bonding · JEE Main previous year questions

Although $\mathrm{C}{\mathrm{N}}^{-}$ ion and ${\mathrm{N}}_2$ molecule are isoelectronic, yet ${\mathrm{N}}_2$ molecule is chemically inert because of

1. A.presence of more number of electrons in bonding orbitals
2. B.low bond energy
3. C.absence of bond polarity
4. D.uneven electron distribution.

1. A.
2. B.
3. C.
4. D.

Which of the following cannot be represented by resonance structures?

1. A.Dimethyl ether
2. B.Nitrate anion
3. C.Carboxylate anion
4. D.Toluene

The $d$-electron configurations of $\mathrm{C}{\mathrm{r}}^{2+}$, $\mathrm{M}{\mathrm{n}}^{2+}$, $\mathrm{F}{\mathrm{e}}^{2+}$ and $\mathrm{C}{\mathrm{o}}^{2+}$ are $d^4$, $d^5$, $d^6$ and $d^7$ respectively. Which one of the following will exhibit the lowest paramagnetic behaviour? (Atomic no. $\mathrm{Cr}=24$, $\mathrm{Mn}=25$, $\mathrm{Fe}=26$, $\mathrm{Co}=27$).

1. A.$[\mathrm{Co}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
2. B.$[\mathrm{Cr}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
3. C.$[\mathrm{Mn}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
4. D.$[\mathrm{Fe}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$

Based on lattice energy and other considerations, which one of the following alkali metal chloride is expected to have the highest melting point?

1. A.$\mathrm{NaCl}$
2. B.$\mathrm{KCl}$
3. C.$\mathrm{LiCl}$
4. D.$\mathrm{RbCl}$

The standard enthalpy of formation of $\mathrm{N}{\mathrm{H}}_3$ is $-46.0\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. If the enthalpy of formation of ${\mathrm{H}}_2$ from its atoms is $-436\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ and that of ${\mathrm{N}}_2$ is $-712\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$, the average bond enthalpy of $\mathrm{N}-\mathrm{H}$ bond in $\mathrm{N}{\mathrm{H}}_3$ is :

1. A.$-964\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
2. B.$+352\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
3. C.$+1056\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
4. D.$-1102\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$

Using MO theory, predict which of the following species has the shortest bond length?

1. A.$O_2^{+}$
2. B.$O_2^{-}$
3. C.$O_2^{2-}$
4. D.$O_2^{2+}$

Which of the following sets of ions represents a collection of isoelectronic species?

1. A.${\mathrm{N}}^{3-},{\mathrm{O}}^{2-},{\mathrm{F}}^{-},{\mathrm{S}}^{2-}$
2. B.$\mathrm{L}{\mathrm{i}}^{+},\mathrm{N}{\mathrm{a}}^{+},\mathrm{M}{\mathrm{g}}^{2+},\mathrm{C}{\mathrm{a}}^{2+}$
3. C.${\mathrm{K}}^{+},\mathrm{C}{\mathrm{l}}^{-},\mathrm{C}{\mathrm{a}}^{2+},\mathrm{S}{\mathrm{c}}^{3+}$
4. D.$\mathrm{B}{\mathrm{a}}^{2+},\mathrm{S}{\mathrm{r}}^{2+},{\mathrm{K}}^{+},\mathrm{C}{\mathrm{a}}^{2+}$

The decreasing values of bond angles from $\mathrm{N}{\mathrm{H}}_3(106^{\circ })$ to $\mathrm{Sb}{\mathrm{H}}_3(91^{\circ })$ down group-15 of the periodic table is due to

1. A.increasing bp-bp repulsion
2. B.increasing p-orbital character in $\mathrm{s}{\mathrm{p}}^3$
3. C.decreasing lp-bp repulsion
4. D.decreasing electronegativity

Of the following sets which one does NOT contain isoelectronic species?

1. A.${\mathrm{BO}}_3^{3-},{\mathrm{CO}}_3^{2-},{\mathrm{NO}}_3^{-}$
2. B.${\mathrm{SO}}_3^{2-},{\mathrm{CO}}_3^{2-},{\mathrm{NO}}_3^{-}$
3. C.${\mathrm{CN}}^{-},{\mathrm{N}}_2,{\mathrm{C}}_2^{2-}$
4. D.${\mathrm{PO}}_4^{3-},{\mathrm{SO}}_4^{2-},{\mathrm{ClO}}_4^{-}$

Lattice energy of an ionic compound depends upon

1. A.Charge on the ion only
2. B.Size of the ion only
3. C.Packing of ions only
4. D.Charge on the ion and size of the ion

Which one of the following species is diamagnetic in nature?

1. A.$\mathrm{H}{\mathrm{e}}_2^{+}$
2. B.${\mathrm{H}}_2$
3. C.${\mathrm{H}}_2^{+}$
4. D.${\mathrm{H}}_2^{-}$

Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour? (At. No. $\mathrm{Cr}=24,\mathrm{Mn}=25,\mathrm{Fe}=26,\mathrm{Co}=27$)

1. A.$[\mathrm{Cr}(\mathrm{CN}{)}_6{]}^{-3}$
2. B.$[\mathrm{Mn}(\mathrm{CN}{)}_6{]}^{-3}$
3. C.$[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{-3}$
4. D.$[\mathrm{Co}(\mathrm{CN}{)}_6{]}^{-3}$

Pick out the isoelectronic structure from the following : $(i)\mathrm{C}{\mathrm{H}}_3^{+}$ $(ii){\mathrm{H}}_3{\mathrm{O}}^{+}$ $(iii)\mathrm{N}{\mathrm{H}}_3$ $(iv)\mathrm{C}{\mathrm{H}}_3^{-}$

1. A.$(i)$ and $(ii)$
2. B.$(iii)$ and $(iv)$
3. C.$(i)$ and $(iii)$
4. D.$(ii)$, $(iii)$ and $(iv)$

Based on lattice energy and other considerations which one of the following alkali metal chlorides is expected to have the highest melting point :

1. A.LiCl
2. B.NaCl
3. C.KCl
4. D.RbCl

Which one of the following sets of ions represents the collection of isoelectronic species? (Atomic nos. : F = 9, Cl = 17, Na = 11, Mg = 12, Al = 13, K = 19, Ca = 20, Sc = 21)

1. A.${\mathrm{K}}^{+},\mathrm{C}{\mathrm{l}}^{-},\mathrm{M}{\mathrm{g}}^{2+},\mathrm{S}{\mathrm{c}}^{3+}$
2. B.$\mathrm{N}{\mathrm{a}}^{+},\mathrm{C}{\mathrm{a}}^{2+},\mathrm{S}{\mathrm{c}}^{3+},{\mathrm{F}}^{-}$
3. C.${\mathrm{K}}^{+},\mathrm{C}{\mathrm{a}}^{2+},\mathrm{S}{\mathrm{c}}^{3+},\mathrm{C}{\mathrm{l}}^{-}$
4. D.$\mathrm{N}{\mathrm{a}}^{+},\mathrm{M}{\mathrm{g}}^{2+},\mathrm{A}{\mathrm{l}}^{3+},\mathrm{C}{\mathrm{l}}^{-}$

The correct order of bond angles (smallest first) in ${\mathrm{H}}_2\mathrm{S},\mathrm{N}{\mathrm{H}}_3,\mathrm{B}{\mathrm{F}}_3$ and $\mathrm{Si}{\mathrm{H}}_4$ is

1. A.${\mathrm{H}}_2\mathrm{S}<\mathrm{Si}{\mathrm{H}}_4<\mathrm{N}{\mathrm{H}}_3<\mathrm{B}{\mathrm{F}}_3$
2. B.${\mathrm{H}}_2\mathrm{S}<\mathrm{N}{\mathrm{H}}_3<\mathrm{B}{\mathrm{F}}_3<\mathrm{Si}{\mathrm{H}}_4$
3. C.${\mathrm{H}}_2\mathrm{S}<\mathrm{N}{\mathrm{H}}_3<\mathrm{Si}{\mathrm{H}}_4<\mathrm{B}{\mathrm{F}}_3$
4. D.$\mathrm{N}{\mathrm{H}}_3<{\mathrm{H}}_2\mathrm{S}<\mathrm{Si}{\mathrm{H}}_4<\mathrm{B}{\mathrm{F}}_3$

The bond order in NO is 2.5 while that in $\mathrm{N}{\mathrm{O}}^{+}$ is 3. Which of the following statements is true for these two species?

1. A.Bond length in $\mathrm{N}{\mathrm{O}}^{+}$ is greater than in NO
2. B.Bond length is unpredictable
3. C.Bond length in $\mathrm{N}{\mathrm{O}}^{+}$ is equal to that in NO
4. D.Bond length in NO is greater than in $\mathrm{N}{\mathrm{O}}^{+}$

Which one the following does not have $\mathrm{s}{\mathrm{p}}^2$ hybridized carbon?

1. A.Acetone
2. B.Acetamide
3. C.Acetonitrile
4. D.Acetic acid

In which of the following species the interatomic bond angle is $109^{\circ }28^{\prime }$ ?

1. A.$\mathrm{N}{\mathrm{H}}_3,\mathrm{B}{\mathrm{F}}_4^{-}$
2. B.$\mathrm{N}{\mathrm{H}}_4^{+},\mathrm{B}{\mathrm{F}}_4^{-}$
3. C.$\mathrm{N}{\mathrm{H}}_3,\mathrm{B}{\mathrm{F}}_3$
4. D.$\mathrm{N}{\mathrm{H}}_2^{-1},\mathrm{B}{\mathrm{F}}_3$

Hybridisation of underlined atom changes in

1. A.$\underline{\mathrm{Al}}{\mathrm{H}}_3$ changes to $\mathrm{Al}{\mathrm{H}}_4^{-}$
2. B.${\mathrm{H}}_2\underline{\mathrm{O}}$ changes to ${\mathrm{H}}_3{\mathrm{O}}^{+}$
3. C.$\underline{\mathrm{N}}{\mathrm{H}}_3$ changes to $\mathrm{N}{\mathrm{H}}_4^{+}$
4. D.in all cases

In which of the following species is the underlined carbon having $\mathrm{s}{\mathrm{p}}^3$ hybridisation?

1. A.$\mathrm{C}{\mathrm{H}}_3\underline{\mathrm{C}}\mathrm{OOH}$
2. B.$\mathrm{C}{\mathrm{H}}_3\underline{\mathrm{C}}{\mathrm{H}}_2\mathrm{OH}$
3. C.$\mathrm{C}{\mathrm{H}}_3\underline{\mathrm{C}}\mathrm{OC}{\mathrm{H}}_3$
4. D.$\mathrm{C}{\mathrm{H}}_2=\underline{\mathrm{C}}\mathrm{H}-\mathrm{C}{\mathrm{H}}_3$

In $\mathrm{Xe}{\mathrm{F}}_2,\mathrm{Xe}{\mathrm{F}}_4,\mathrm{Xe}{\mathrm{F}}_6$ the number of lone pairs of Xe are respectively :

1. A.2, 3, 1
2. B.1, 2, 3
3. C.4, 1, 2
4. D.3, 2, 1

Number of sigma bonds in ${\mathrm{P}}_4{\mathrm{O}}_{10}$ is :

1. A.6
2. B.7
3. C.17
4. D.16