If molecule a has a bond enthalpy of 418 kj/mol and molecule b has a bond enthalpy of 941 kj/mol, what can be said of molecule a compared to molecule b

Since molecule b has greater bond enthalpy (941 kj/mol) compared to molecule a (418 kj/mol) so the bond length of molecule b is shorter compared too molecule a which has a lower bond enthalphy. This also means that molecule a could be greater in size than molecule b.