Question

The wavelength of $ {{K}_{a}} $ X-rays for lead isotopes $ P{{b}^{208}},\text{ }P{{b}^{206}} $ and $ P{{b}^{204}} $ are $ {{\lambda }_{1}},{{\lambda }_{2}} $ and $ {{\lambda }_{3}} $ respectively. Then

• A. $ {{\lambda }_{1}}={{\lambda }_{2}}={{\lambda }_{3}} $
• B. $ {{\lambda }_{1}}>{{\lambda }_{2}}>{{\lambda }_{3}} $
• C. $ {{\lambda }_{1}}<{{\lambda }_{2}}<{{\lambda }_{3}} $
• D. $ {{\lambda }_{1}}={{\lambda }_{2}}>{{\lambda }_{3}} $

Answer 1

Answer: (A)

The wavelength of X-rays depends on the atomic number Z. Since, isotopes are the elements which have same atomic number. So, $ {{\lambda }_{1}}={{\lambda }_{2}}={{\lambda }_{3}} $