Chemical Bonding · JEE Main previous year questions

The ${\left(\frac{\partial E}{\partial T}\right)}_p$ of different types of half cells are as follows: | A | B | C | D | |---|---|---|---| | $1\times 10^{-4}$ | $2\times 10^{-4}$ | $0.1\times 10^{-4}$ | $0.2\times 10^{-4}$ | (Where E is the electromotive force) Which of the above half cells would be preferred to be used as reference electrode?

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

Amongst $\mathrm{S}{\mathrm{F}}_4$, $\mathrm{Xe}{\mathrm{F}}_4$, $\mathrm{C}{\mathrm{F}}_4$ and ${\mathrm{H}}_2\mathrm{O}$, the number of species with two lone pairs of electrons is ____.

The pair, in which ions are isoelectronic with ${\mathrm{Al}}^{3+}$ is :

1. A.${\mathrm{Br}}^{-}$ and ${\mathrm{Be}}^{2+}$
2. B.${\mathrm{Cl}}^{-}$ and ${\mathrm{Li}}^{+}$
3. C.${\mathrm{S}}^{2-}$ and ${\mathrm{K}}^{+}$
4. D.${\mathrm{O}}^{2-}$ and ${\mathrm{Mg}}^{2+}$

Amongst $\mathrm{Be}{\mathrm{F}}_2$, $\mathrm{B}{\mathrm{F}}_3$, ${\mathrm{H}}_2\mathrm{O}$, $\mathrm{N}{\mathrm{H}}_3$, $\mathrm{CC}{\mathrm{l}}_4$ and $\mathrm{HCl}$, the number of molecules with non-zero net dipole moment is ____.

The correct order of bond orders of ${\mathrm{C}}_2^{2-}$, ${\mathrm{N}}_2^{2-}$ and ${\mathrm{O}}_2^{2-}$ is, respectively

1. A.${\mathrm{C}}_2^{2-}<{\mathrm{N}}_2^{2-}<{\mathrm{O}}_2^{2-}$
2. B.${\mathrm{O}}_2^{2-}<{\mathrm{N}}_2^{2-}<{\mathrm{C}}_2^{2-}$
3. C.${\mathrm{C}}_2^{2-}<{\mathrm{O}}_2^{2-}<{\mathrm{N}}_2^{2-}$
4. D.${\mathrm{N}}_2^{2-}<{\mathrm{C}}_2^{2-}<{\mathrm{O}}_2^{2-}$

Number of paramagnetic oxides among the following given oxides is ____. $\mathrm{L}{\mathrm{i}}_2\mathrm{O}$, $\mathrm{CaO}$, $\mathrm{N}{\mathrm{a}}_2{\mathrm{O}}_2$, $\mathrm{K}{\mathrm{O}}_2$, $\mathrm{MgO}$ and ${\mathrm{K}}_2\mathrm{O}$

1. A.1
2. B.2
3. C.3
4. D.0

The bond order and magnetic behaviour of $O_2^{-}$ ion are respectively :

1. A.$1.5$ and paramagnetic
2. B.$1.5$ and diamagnetic
3. C.$2$ and diamagnetic
4. D.$1$ and paramagnetic

Given below are two statements : Statement I : $[Mn(CN{)}_6{]}^{3-}$, $[Fe(CN{)}_6{]}^{3-}$ and $[Co(C_2{O}_4{)}_3{]}^{3-}$ are ${\mathrm{d}}^2\mathrm{s}{\mathrm{p}}^3$ hybridised. Statement II : $[MnC{l}_6{]}^{3-}$ and $[Fe{F}_6{]}^{3-}$ are paramagnetic and have 4 and 5 unpaired electrons, respectively. In the light of the above statements, choose the correct answer from the options given below :

1. A.Statement I is correct but statement II is false
2. B.Both statement I and Statement II are false
3. C.Statement I is incorrect but statement II is true
4. D.Both statement I and statement II are true

The number of sigma bonds in $${\mathrm{H}}_3\mathrm{C}-\underset{\mathrm{H}}{\underset{|}{\mathrm{C}}}=\mathrm{CH}-\mathrm{C}\equiv \mathrm{C}-\mathrm{H}$$ is ____.

In the following the correct bond order sequence is :

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

The set having ions which are coloured and paramagnetic both is :

1. A.$\mathrm{C}{\mathrm{u}}^{2+},\mathrm{C}{\mathrm{r}}^{3+},\mathrm{S}{\mathrm{c}}^{+}$
2. B.$\mathrm{C}{\mathrm{u}}^{2+},\mathrm{Z}{\mathrm{n}}^{2+},\mathrm{M}{\mathrm{n}}^{4+}$
3. C.$\mathrm{S}{\mathrm{c}}^{3+},{\mathrm{V}}^{5+},\mathrm{T}{\mathrm{i}}^{4+}$
4. D.$\mathrm{N}{\mathrm{i}}^{2+},\mathrm{M}{\mathrm{n}}^{7+},\mathrm{H}{\mathrm{g}}^{2+}$

According to the valence bond theory the hybridization of central metal atom is ${\text{dsp}}^2$ for which one of the following compounds?

1. A.${\text{NiCl}}_2\cdot 6{\text{H}}_2\text{O}$
2. B.${\text{K}}_2[\text{Ni}(\text{CN}{)}_4]$
3. C.$[\text{Ni}(\text{CO}{)}_4]$
4. D.${\text{Na}}_2[{\text{NiCl}}_4]$

A s-block element (M) reacts with oxygen to form an oxide of the formula ${\text{MO}}_2$. The oxide is pale yellow in colour and paramagnetic. The element (M) is :

1. A.Mg
2. B.Na
3. C.Ca
4. D.K

The number of lone pairs of electrons on the central I atom in ${\text{I}}_3^{-}$ is ________.

1. A.$\mathrm{s}{\mathrm{p}}^3,\mathrm{s}{\mathrm{p}}^2,\mathrm{s}{\mathrm{p}}^2$
2. B.$\mathrm{s}{\mathrm{p}}^3,\mathrm{sp},\mathrm{s}{\mathrm{p}}^2$
3. C.$\mathrm{s}{\mathrm{p}}^3,\mathrm{s}{\mathrm{p}}^2,\mathrm{sp}$
4. D.$\mathrm{s}{\mathrm{p}}^3,\mathrm{sp},\mathrm{sp}$

The secondary valency and the number of hydrogen bonded water molecule(s) in $\mathrm{CuS}{\mathrm{O}}_4\cdot 5{\mathrm{H}}_2\mathrm{O}$, respectively, are :

1. A.5 and 1
2. B.4 and 1
3. C.6 and 5
4. D.6 and 4

Match List - I with List - II : $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ \text{(a)}& \mathrm{Be}& \text{(i)}& \text{treatment of cancer}\\ \text{(b)}& \mathrm{Mg}& \text{(ii)}& \text{extraction of metals}\\ \text{(c)}& \mathrm{Ca}& \text{(iii)}& \text{incendiary bombs and signals}\\ \text{(d)}& \mathrm{Ra}& \text{(iv)}& \text{windows of X-ray tubes}\\ & & \text{(v)}& \text{bearings for motor engines}\end{array}$$ Choose the most appropriate answer from the options given below :

1. A.(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
2. B.(a)-(iii), (b)-(iv), (c)-(v), (d)-(ii)
3. C.(a)-(iii), (b)-(iv), (c)-(ii), (d)-(v)
4. D.(a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

The number of species below that have two lone pairs of electrons in their central atom is ____. (Round off to the Nearest Integer). $\mathrm{S}{\mathrm{F}}_4$, $\mathrm{B}{\mathrm{F}}_4^{-}$, $\mathrm{Cl}{\mathrm{F}}_3$, $\mathrm{As}{\mathrm{F}}_3$, $\mathrm{PC}{\mathrm{l}}_5$, $\mathrm{Br}{\mathrm{F}}_5$, $\mathrm{Xe}{\mathrm{F}}_4$, $\mathrm{S}{\mathrm{F}}_6$

A xenon compound 'A' upon partial hydrolysis gives $\mathrm{Xe}{\mathrm{O}}_2{\mathrm{F}}_2$. The number of lone pair of electrons present in compound A is ____. (Round off to the Nearest Integer)

Given below are two statements : one is labeled as Assertion A and the other is labelled as Reason R : Assertion A : The $\mathrm{H}-\mathrm{O}-\mathrm{H}$ bond angle in water molecule is $104.5^{\circ }$. Reason R : The lone pair - lone pair repulsion of electrons is higher than the bond pair - bond pair repulsion. In the light of the above statements, choose the correct answer from the options given below :

1. A.Both A and R are true, and R is the correct explanation of A
2. B.A is true but R is false
3. C.A is false but R is true
4. D.Both A and R are true, but R is not the correct explanation of A

Assertion A : Enol form of acetone $[\mathrm{C}{\mathrm{H}}_3\mathrm{COC}{\mathrm{H}}_3]$ exists in $<0.1\%$ quantity. However, the enol form of acetyl acetone $[\mathrm{C}{\mathrm{H}}_3\mathrm{COC}{\mathrm{H}}_2\mathrm{OCC}{\mathrm{H}}_3]$ exists in approximately $15\%$ quantity. Reason R : Enol form of acetyl acetone is stabilized by intramolecular hydrogen bonding, which is not possible in enol form of acetone. Choose the correct statement :

1. A.Both A and R are true but R is not the correct explanation of A
2. B.A is true but R is false
3. C.A is false but R is true
4. D.Both A and R are true and R is the correct explanation of A

In chromotography technique, the purification of compound is independent of :

1. A.Solubility of the compound
2. B.Mobility or flow of solvent system
3. C.Physical state of the pure compound
4. D.Length of the column or TLC plate

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Dipole-dipole interactions are the only non-covalent interactions, resulting in hydrogen bond formation. Reason R : Fluorine is the most electronegative element and hydrogen bonds in HF are symmetrical. In the light of the above statements, choose the most appropriate answer from the options given below :

1. A.Both A and R are true and R is the correct explanation of A
2. B.A is true but R is false
3. C.A is false but R is true
4. D.Both A and R are true but R is NOT the correct explanation of A

Given below are two statements : Statement I : o-Nitrophenol is steam volatile due to intramolecular hydrogen bonding. Statement II : o-Nitrophenol has high melting due to hydrogen bonding. In the light of the above statements, choose the most appropriate answer from the options given below :

1. A.Both Statement I and Statement II are true
2. B.Statement I is true but Statement II is false
3. C.Statement I is false but Statement II is true
4. D.Both Statement I and Statement II are false

Match List - I with List - II. | List - I (Molecule) | List - II (Bond order) | | :--- | :--- | | (a) $N{e}_2$ | (i) 1 | | (b) $N_2$ | (ii) 2 | | (c) $F_2$ | (iii) 0 | | (d) $O_2$ | (iv) 3 | Choose the correct answer from the options given below :

1. A.(a) $\to$ (i), (b) $\to$ (ii), (c) $\to$ (iii), (d) $\to$ (iv)
2. B.(a) $\to$ (iv), (b) $\to$ (iii), (c) $\to$ (ii), (d) $\to$ (i)
3. C.(a) $\to$ (iii), (b) $\to$ (iv), (c) $\to$ (i), (d) $\to$ (ii)
4. D.(a) $\to$ (ii), (b) $\to$ (i), (c) $\to$ (iv), (d) $\to$ (iii)