Which of the following has the strongest bond? A.HF B.HCl C.HBr D.HI
Hint: For the bond to be stronger, the bond enthalpy should be more and acidic strength should be low. When we go down in the periodic table, the atoms get larger and acidic strength gets stronger which means the bond strength decreases.
Complete step by step answer: The bond strength depends upon the following factors: When bond order is large, then bond length will be small. The stronger will be the nature of bond. When bond angle is small, larger will be the bond length. Then the strength of the bond will be weaker. The stability of acids decreases due to decrease in bond dissociation enthalpy of $H - X$ bond from $HF$ to $HI$. Therefore, the acidic strength increases from $HF$ to $HI$. The order of acidic character of halogens is $H - I < H - Br < H - Cl < H - F$ Since, $H - I$ is the strongest acid the bond enthalpy decreases and hence $H - I$ is the weakest bond. Therefore, $H - F$ is the weakest acid the bond enthalpy increases so, $H - F$ is the strongest bond. Therefore, option (A) is correct.
Note:The bond strength depends upon the bond enthalpy.Bond strength can be explained, in chemistry, as the strength with which a chemical bond holds two atoms together. This is conventionally measured in terms of the amount of energy, in kilocalories per mole, required to break the bond.