Monochromatic X-rays reflected from a calcite crystal (lattice constant ? = 3? ) give rise to first order Bragg reflection at 6.7?. The wavelength of these X-rays will be

Monochromatic X-rays reflected from a calcite crystal (lattice constan

1.	Monochromatic X-rays reflected from a calcite crystal (lattice constant ? = 3? ) give rise to first order Bragg reflection at 6.7?. The wavelength of these X-rays will be
A.	7A
B.	170 A
C.	70 A
D.	0.7 A
E.	0.07 A
Answer» E. 0.07 A