Properties

With the exception of He, which has 2 valence electrons, the closed shell/noble gas configuration has eight electrons in its valence shell.

Because H is more electronegative than B, H has a partial negative charge.

Because Cl is in period 3 and F is in period 2, the Cl atom is larger than the F atom. This means that the Cl-Cl bond should be larger.

Because F is both smaller and more electronegative than Cl, it should have a shorter and stronger bond with H than has Cl.