<span>Calcium crystal has a face center cubic (FCC) structure. For FCC structure, relation between edge length (a) and radius (r) is a = 2</span>√2 r <span>Given: r = 180 pm Therefore, a = 2</span>√2 180 <span> = 2 x 1.141 x 180 = 410.76 pm
</span><span>The length of the edge of the Ca unit cell is 410.76 pm.</span><span>