Q. The wavelengths of -rays for lead isotopes and are and respectively. Then

 1920  210 AIIMSAIIMS 2009Atoms Report Error

Solution:

Wavelengths of the lines for given isotopes of lead (Pb) can be given by a general expression

where Rydberg's constant, atomic number of the isotopes. Though and have different atomic masses, will be same for them i.e. .

and