Question

The wavelength of $K_a$ X-rays for lead isotopes $P{b}^{208},P{b}^{206}$ 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, ${\lambda }_1={\lambda }_2={\lambda }_3$