Which of the following crystal systems does not possess an axis of rotation?

Number of crystal systems from the following where body-centered unit cell can be found,is $.........$ Cubic,tetragonal,orthorhombic,hexagonal,rhombohedral,monoclinic,triclinic.

$A$ metal has a $bcc$ structure. If the edge length of its unit cell is $3.04 \ \overset{\circ}{A}$,what is the volume of the unit cell in $cm^3$?

Explain the concept of a two-dimensional lattice and a hypothetical two-dimensional crystal.

The total number of body-centred lattices possible among the $14$ Bravais lattices is:

Find the Weiss indices for the plane $(231)$.