Covalent bond - Lewis structures, formal charge and bond parameters — NEET & JEE Questions

Question 1 · difficulty L1 · recall

A covalent bond is formed primarily by

• A. sharing of electron pairs between atoms
• B. complete transfer of protons
• C. loss of all valence electrons by both atoms
• D. sharing of neutrons

Question 2 · difficulty L2 · understanding

The covalent radii of atoms $A$ and $B$ are $r_A$ and $r_B$, respectively. The covalent bond length and total length of AB molecule are respectively

• A. $\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right), 2\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right)$
• B. $\frac{1}{2}\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right),\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right)$
• C. $\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right),\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right)$
• D. $2\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right), \frac{1}{2}\left(\mathrm{r}_{\mathrm{A}}+\mathrm{r}_{\mathrm{B}}\right)$

Question 3 · difficulty L2 · understanding

The correct increasing order of C–H(A), C–O(B), C=O(C) and C≡N(D) bonds in terms of covalent bond length is :

• A. D < C < B < A
• B. D < C < A < B
• C. A < B < C < D
• D. A < D < C < B

Question 4 · difficulty L2 · understanding

Given below are two statements : Statement (I) : Experimentally determined oxygen-oxygen bond lengths in the $\mathrm{O}_3$ are found to be same and the bond length is greater than that of a $\mathrm{O}=\mathrm{O}$ (double bond) but less than that of a single $(\mathrm{O}-\mathrm{O})$ bond. Statement (II) : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond $(\mathrm{O}=\mathrm{O})$ but more than that of a single bond $(\mathrm{O}-\mathrm{O})$. In the light of the above statements, choose the correct answer from the options given below :

• A. Statement I is false but Statement II is true
• B. Both Statement I and Statement II are true
• C. Statement I is true but Statement II is false
• D. Both Statement I and Statement II are false

Question 5 · difficulty L2 · understanding

The bond dissociation energy is highest for

• A. Cl$$_2$$
• B. I$$_2$$
• C. Br$$_2$$
• D. F$$_2$$

Question 6 · difficulty L2 · understanding

Given below are two statements : one is labeled as Assertion A and the other is labelled as Reason R : Assertion A : The H$$-$$O$$-$$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 :

• A. Both A and R are true, and R is the correct explanation of A
• B. A is true but R is false
• C. A is false but R is true
• D. Both A and R are true, but R is not the correct explanation of A

Question 7 · difficulty L2 · understanding

Number of $$\sigma$$ and $$\pi$$ bonds present in ethylene molecule is respectively :

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

Question 8 · difficulty L2 · understanding

Given below are two statements. Statement I: $$\mathrm{O}_{2}, \mathrm{Cu}^{2+}$$, and $$\mathrm{Fe}^{3+}$$ are weakly attracted by magnetic field and are magnetized in the same direction as magnetic field. Statement II: $$\mathrm{NaCl}$$ and $$\mathrm{H}_{2} \mathrm{O}$$ are weakly magnetized in opposite direction to magnetic field. In the light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement I and Statement II are correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is correct but Statement II is incorrect.
• D. Statement I is incorrect but Statement II is correct.

Question 9 · difficulty L2 · understanding

Arrange the following in increasing order of their covalent character. A. $$\mathrm{CaF}_{2}$$ B. $$\mathrm{CaCl}_{2}$$ C. $$\mathrm{CaBr}_{2}$$ D. $$\mathrm{CaI}_{2}$$ Choose the correct answer from the options given below.

• A. B < A < C < D
• B. A < B < C < D
• C. A < B < D < C
• D. A < C < B < D

Question 10 · difficulty L2 · understanding

The option(s) in which at least three molecules follow Octet Rule is(are)

• A. $\mathrm{CO}_2, \mathrm{C}_2 \mathrm{H}_4, \mathrm{NO}$ and $\mathrm{HCl}$
• B. $\mathrm{NO}_2, \mathrm{O}_3, \mathrm{HCl}$ and $\mathrm{H}_2 \mathrm{SO}_4$
• C. $\mathrm{BCl}_3, \mathrm{NO}, \mathrm{NO}_2$ and $\mathrm{H}_2 \mathrm{SO}_4$
• D. $\mathrm{CO}_2, \mathrm{BCl}_3, \mathrm{O}_3$ and $\mathrm{C}_2 \mathrm{H}_4$