Question

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 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:

(a) A is false but R is true

(b) Both A and R are true and R is the correct explanation of A

(c) A is true but R is false

(d) Both A and R are true and R is not the correct explanation of A

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

Answer 1

Answer: (A)

• Dipole - Dipole are not only the interaction responsible for hydrogen bond formation. Ion-dipole can also be responsible for hydrogen bond formation.
• F is most electronegative element and anhydrous $HF$ in solid phase has symmetrical hydrogen bonding. The strongest H-bonds are formed by F-atoms. Some hydrogen bonding also occurs in the gas, which consists of a mixture of cyclic $(HF{)}_6$ polymers, dimeric $(HF{)}_2$, and monomeric $HF.$

Hence, option (a) is the correct answer.