Q. Lithium metal crystallises in a body centred cubic crystal. If the length of the side of the unit cell of lithium is 351 pm, the atomic radius of the lithium will be:
A) 151.8 pm
B) 75.5 pm
C) 300.5 pm
D) 240.8 pm
Explanation
[Solution from source] In bcc the atoms touch along the body diagonal: 4r = √3a. r = 1.732 × 351/4 ≈ 152 pm, matching 151.8 pm. 75.5 pm and 300.5 pm come from wrong geometric relations. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.