First order X-ray reflection `(lambda=154pm)` is maximum from a set of (2,0,0) planes of a bcc lattice was observed at `16^(0)6^(1)`. Then the edge length of unit cell is `(Sin 16^(0)6^(1)=0.2773)`

Options

A. 360 pm
B. 420 pm
C. 560 pm
D. 180 pm

Answer

C

Explanation

For first order difraction, `n = 1 lamda = 2d sin theta `
`d = (lamda)/(2 sin theta) = (154)/(2 xx 0.2773) = 280` pm
`d_(2,0,0) = (2)/(sqrt(2^2 + 0^2 + 0^2) ) rArr a = 2 xx 280 = 560 ` pm