Lithium borohydride $\left(LiB{H}_{4}\right),$crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are : a = 6.81Å, b= 4.43Å, c=7.17Å. If the molar mass of $LiB{H}_{4}$ is 21.76 g mol–1. The density of the crystal is –

(1) 0.668 g cm–3

(2) 0.585 g cm2

(3) 1.23 g cm–3

(4) None