Question
The emission spectrum of hydrogen is found to satisfy the expression for the energy change $$\Delta E$$ ( in joules ) such that $$\Delta E = 2.18 \times {10^{ - 18}}\left( {\frac{1}{{{n_1}^2}} - \frac{1}{{{n_2}^2}}} \right)J$$ where $${n_1} = 1,2,3,...$$ and $${n_2} = 2,3,4.$$ The spectral lines corresponds to Paschen series if
A.
$${n_1} = 1\,\,{\text{and}}\,\,{n_2} = 2,3,4$$
B.
$${n_1} = 3\,\,{\text{and}}\,\,{n_2} = 4,5,6$$
C.
$${n_1} = 1\,\,{\text{and}}\,\,{n_2} = 3,4,5$$
D.
$${n_1} = 2\,\,{\text{and}}\,\,{n_2} = 3,4,5$$
Answer :
$${n_1} = 3\,\,{\text{and}}\,\,{n_2} = 4,5,6$$
Solution :
Paschen, $${n_1} = 3;{n_2} = 4,5\,......;$$ region-infrared.