Kα wavelength emitted by an atom of atomic number Z = 11 is λ. The atomic number for an atom that emits Kα radiation with wavelength 4λ is
Z=6
Z=4
Z=11
Z=44
f1=vλ1=a(11−1) and f2=vλ2=a(Z−1)
By dividing, λ2λ1=10Z−1 ⇒41=10Z−1 ⇒Z=6