Question

In a hydrogen sample, electrons fall from the $7^{th}$ shell. Select the correct statement(s):

• A. 6 lines belong to visible range
  
• B. 6 lines are shorter in wavelength than all lines of Balmer series produced here
  
• C. 17 lines do not belong to Paschen series
  
• D. Sum of the lines that belong to the Brackett and Pfund series is equal to lines that belong in the visible range

Answer 1

Answer: (B), (C), (D)

Sum of the lines that belong to the Brackett and Pfund series is equal to lines that belong in the visible range

Number of lines corresponding to:
Lyman series = 7-1 = 6
Balmer series = 7-2 = 5
Paschen series = 7-3 = 4
Brackett series = 7-4 = 3
Pfund series = 7-5 = 2
Another transition = 7-6 = 1
Total lines = 21
(a) Lines that appear in the Balmer series are visible.
(b) Lyman series are shorter in wavelength than Balmer series.
(c) 17 lines do not belong to Paschen series.
(d) Brackett series + Pfund series = Balmer series