(a) 1 (6)30 (C)45 (d) 60° . An X-ray difraction (XRD) Cxperiment is carried out on a crystalline solid having FCC structure at room tem perature. The solid undergoes a phase transformationon cooling to-20° C and shows orthorhombic structur with small decrease in its unit cell lengths as compared to the FCC unit cell lengths. As a result, the (311) line o the XRD pattern corresponding to the FCC system JAM 2011] (a) will split into a doublet. (C)will remain unchanged. (b) will split into a triplet. (d) will split into two separate doublets.