Question

which bond would you expect to have the lowest bond energy?
o h-f
o h-br
o h-i
o h-cl

Explanation:

Step1: Recall bond energy trend

Bond energy is related to bond length. Longer bonds have lower energy. Bond length increases with larger atomic size of the halogen (since H - X bonds, X: F, Cl, Br, I). Atomic size: I > Br > Cl > F.

Step2: Determine bond length

For H - F, H - Cl, H - Br, H - I, the halogen I has the largest atomic radius, so H - I bond is the longest.

Step3: Relate bond length to energy

Longer bond length means lower bond energy. So H - I has the lowest bond energy.

Answer:

H-I (the option with the blue dot, labeled H-I)