Polarity, dipole moment and Fajans' rules — practice questions

Question 1 · difficulty L2 · understanding

Number of compounds from the following with zero dipole moment is _________. $$\mathrm{HF}, \mathrm{H}_2, \mathrm{H}_2 \mathrm{~S}, \mathrm{CO}_2, \mathrm{NH}_3, \mathrm{BF}_3, \mathrm{CH}_4, \mathrm{CHCl}_3, \mathrm{SiF}_4, \mathrm{H}_2 \mathrm{O}, \mathrm{BeF}_2$$

Question 2 · difficulty L2 · understanding

Number of compounds / species from the following with non-zero dipole moment is _________. $$\mathrm{BeCl}_2, \mathrm{BCl}_3, \mathrm{NF}_3, \mathrm{XeF}_4, \mathrm{CCl}_4, \mathrm{H}_2 \mathrm{O}, \mathrm{H}_2 \mathrm{~S}, \mathrm{HBr}, \mathrm{CO}_2, \mathrm{H}_2, \mathrm{HCl}$$

Question 3 · difficulty L2 · understanding

The total number of molecules with zero dipole moment among $$\mathrm{CH}_4, \mathrm{BF}_3, \mathrm{H}_2 \mathrm{O}, \mathrm{HF}, \mathrm{NH}_3, \mathrm{CO}_2$$ and $$\mathrm{SO}_2$$ is ________.

Question 4 · difficulty L2 · understanding

Amongst the following, the number of molecule/(s) having net resultant dipole moment is ____________. NF 3 , BF 3 , BeF 2 , CHCl 3 , H 2 S, SiF 4 , CCl 4 , PF 5

Question 5 · difficulty L2 · understanding

Amongst BeF 2 , BF 3 , H 2 O, NH 3 , CCl 4 and HCl, the number of molecules with non-zero net dipole moment is ____________.

Question 6 · difficulty L2 · understanding

Which one of the following molecules has maximum dipole moment?

• A. $$\mathrm{CH}_4$$
• B. $$\mathrm{NF}_3$$
• C. $$\mathrm{NH}_3$$
• D. $$\mathrm{PF}_5$$

Question 7 · difficulty L2 · understanding

Choose the polar molecule from the following:

• A. $$\mathrm{CCl}_4$$
• B. $$\mathrm{CO}_2$$
• C. $$\mathrm{CH}_2=\mathrm{CH}_2$$
• D. $$\mathrm{CHCl}_3$$

Question 8 · difficulty L2 · understanding

Statement I : Dipole moment is a vector quantity and by convention it is depicted by a small arrow with tail on the negative centre and head pointing towards the positive centre. Statement II : The crossed arrow of the dipole moment symbolizes the direction of the shift of charges in the molecules. In the light of the above statements, choose the most appropriate answer from the options given below :

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

Question 9 · difficulty L2 · understanding

Match List - I with List - II. List - I List - II (A) $$\psi_{\mathrm{MO}}=\psi_{\mathrm{A}}-\psi_{\mathrm{B}}$$ (I) Dipole moment (B) $$\mu=Q \times r$$ (II) Bonding molecular orbital (C) $$\frac{\mathrm{N}_{\mathrm{b}}-\mathrm{N}_{\mathrm{a}}}{2}$$ (III) Anti-bonding molecular orbital (D) $$\psi_{\mathrm{MO}}=\psi_{\mathrm{A}}+\psi_{\mathrm{B}}$$ (IV) Bond order Choose the correct answer from the options given below :

• A. $$(\mathrm{A})-(\mathrm{II}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{IV}),(\mathrm{D})-(\mathrm{III})$$
• B. $$(\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{II})$$
• C. $$(\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{IV}),(\mathrm{D})-(\mathrm{II})$$
• D. $$(\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{I})$$

Question 10 · difficulty L2 · understanding

The correct order of dipole moments for the given species is

• A. BF$_3$ = NH$_4^+$ < NF$_3$ < NH$_3$
• B. BF$_3$ < NH$_4^+$ < NF$_3$ < NH$_3$
• C. NH$_4^+$ < BF$_3$ < NH$_3$ < NF$_3$
• D. BF$_3$ < NH$_4^+$ < NH$_3$ < NF$_3$