Select the incorrect statement about ABAB ...... type two dimensional arrangement (two dimensional hexagonal unit cell)

Coordination Number of arrangement is 6

There are some voids (empty spaces) and they are called triangular void

Packing efficiency of the arrangement is 'π32'

Maximum radius of foreign atom that can be placed in two dimensional void  generated above arrangement without disturbing the crystal, will be 0.155 R (R = radius of host atom)