Answer
C-Cl is the weakest bond in the chart.
H-F is the most stable bond in the chart
Step-by-step explanation
As bond strength increases, the atoms in the bond are pulled more tightly together. Therefore, generally, as the bond energy increases, the bond length decreases. The strength of a bond between two atoms increases as the number of electron pairs in the bond increases.
So, the bond energy is directly related to the strength of a chemical bond. High bond energy means that a bond is strong and the molecule that contains that bond is likely to be stable and less reactive.
Hence, C-Cl is the weakest bond in the chart because it has the least bond energy (339 kJ/mol) and H-F is the most stable bond in the chart because it has the highest bond energy (565 kJ/mol).