Solution:
SOLUTION
atomic number of an element Z1?=11
a wavelength of an elementλ1?=λ
the atomic number of the second element Z2?=?
a wavelenght of the second element λ2?=4λ
According to Moseley's law v?=a(z−b)
or (z2?−1)2=25 or z2?=6
So the atomic number of the second elementZ2?=6
