The wavelengths of the $K_\alpha$ X-ray radiations from two sources $P$ and $Q$ are $1.50 Ã…$ and $0.75 Ã…\left(1 Ã…=10^{-10} \mathrm{~m}\right)$. Then most likely,

• A

  $P={ }_{41} \mathrm{Nb} ; Q={ }_{29} \mathrm{Cu}$
• B

  $P={ }_{29} \mathrm{Cu} ; Q={ }_{47} \mathrm{Ag}$
• Correct answer
  C

  $P={ }_{29} \mathrm{Cu} ; Q={ }_{41} \mathrm{Nb}$
• D

  $P={ }_{41} \mathrm{Nb} ; Q={ }_{27} \mathrm{Co}$

Hence, the correct answer is option: 'C'.