KVPY SX SB Exam 19-Nov-2017 Question Paper

The emission series of hydrogen atom is given by
$\frac{1}{\mathit{\lambda }}=\mathit{R}\left(\frac{1}{{\mathit{n}}_1^2}-\frac{1}{{\mathit{n}}_2^2}\right)$
where R is the Rydberg constant. For a transition from ${\mathit{n}}_2\mathrm{to}{\mathit{n}}_1$, the relative change $\frac{∆\mathit{\lambda }}{\mathit{\lambda }}$ in the emission wavelength if hydrogen is replaced by deuterium (assume that the mass of proton and neutron are the same and approximately 2000 times larger than that of electrons) is