By definition “X” is not an alkaline earth metal. Hydride of “X” cannot be prepared by direct combination with hydrogen. “X” renders passive with concentrated HNO3.  Nature of Oxide of “X” is

“BeO” is amphoteric, other oxides of 2nd group are basic. ∴ By definition “Be” cannot be called as alkaline earth  metal; BeH2 cannot be prepared directly;  “Be” renders passive with concentrated HNO3 due to the formation of oxide layer;