They are the elements from scandium to copernicium. The elements between group 2 and group 3
COVALENT BOND IS THE BOND EXISTING BETWEEN 2 ATOMS THAT SHARE 6 ELECTRONS
The correct answer is the fourth option. The complete dissociation of a strong base is BOH + h20 -> B+ + OH- + H20 since this is the only base from the choices given. A base is a substance that accepts hydrogen ions.