1) The wave number of first emission line in the Balmer series of H- spectrum is (R= Rydberg constant) A) $\frac{5}{36}R$ B) $\frac{9}{400}R$ C) $\frac{7}{6}R$ D) $\frac{3}{4}R$ Answer: Option AExplanation:$\overline{v}= RZ^{2}\left( \frac{1}{2^{2}}-\frac{1}{3^{2}}\right)$ $= R\left( \frac{1}{4}-\frac{1}{9}\right)=\frac{5R}{36}$
