Name the element which is invariably bivalent and whose oxide is soluble in excess of NaOH and its dipositive ion has noble gas core .

Name the element which is invariably bivalent and whose oxide is solub

1.	Name the element which is invariably bivalent and whose oxide is soluble in excess of NaOH and its dipositive ion has noble gas core .
Answer» Solution :Be . It forms bivalent ion which has helium gas CORE . `underset(2,2) (Be) to underset(2) (Be^(2+))` (has He gas ore) `+ 2 e^-` Being slightly acidic , it dissolves in excess of Na OH to form sodium berrylate . `BEO + 2 NaOH to underset("Sod. berrylate") (Na_(2)BeO_(2)) + H_(2)O`