In any group second period element exhibit anomalous properties. Correct statements about this is/are.

Generally maximum covalence of the first member of each group cannot exceed four

The first member of p-block element displays greater ability to form $p\pi -d\pi$ multiple bonds than second member

Anomalous behavior is due to small size, large charge/radius ratio and high electro negativity of the elements

All second period elements exhibit diagonal relationship.