When $O_2$ is adsorbed on a metallic surface, electron transfer occurs from the metal to $O_2$. The TRUE statement(s) regarding this adsorption is(are)

During transfer of $e^{-}$ adsorption is exothermic. During Electronic transfer metal to ${\pi }^{\ast }2p\text{ of }{O}_2$ of  molecule Bond order of $O_2$ decreases, and hence increasing O-O bond length.