Question

K_a wavelength of an unknown element is.0709 nm. Identify the element-

• A. Co
• B. Cu
• C. Mn
• D. Mo

Answer 1

Answer: (D)

Mo

Answer 2

f = = $\frac { 3 \times 10 ^ { 8 } } { 0.0709 \times 10 ^ { - 9 } }$ = 4.23 × 10¹⁸ Hz

From Moseley's law Z = 1 + $\sqrt { \frac { \mathrm { f } } { 2.48 \times 10 ^ { 5 } } }$

\ Z = 42 corresponds to Mo.