## Case Study Questions for Class 12 Physics Chapter 12 Atoms

**Case Study Question 1:**

The spectral series of hydrogen atom were accounted for by Bohr using the relation

where, R=Rydberg constant = 1.097 x 10^{7} m^{-1}

Lyman series is obtained when an electron jumps to first orbit from any subsequent orbit. Similarly, Balmer series is obtained when an electron jumps to 2^{nd} orbit from any subsequent orbit. Paschen series is obtained when an electron jumps to 3^{rd} orbit from any subsequent orbit. Whereas Lyman series in U.V. region, Balmer series is in visible region and Paschen series lies in infrared region. Series limit is obtained when n_{2}=âˆž.

(i) The wavelength of first spectral line of Lyman series is

(a) 1215.4 A^{0}

(b) 1215.4 cm

(c) 1215.4 m

(d) 1215. 4 mm

(ii) The wavelength limit of Lyman series is

(a) 1215.4 A^{0}

(b) 511.9 A^{0}

(c) 951.6 A^{0}

(d) 911.6 A^{0}

(iii) The frequency of first spectral line of Balmer series is

(a) 1.097 x 10^{7} Hz

(b) 4.57 x 10^{14} Hz

(c) 4.57 x 10^{15} Hz

(d) 4.57 x 10^{16} Hz

(iv) Which of the following transitions in hydrogen atom emit photon of highest frequency?

(a) n=1 to n=2

(b) n=2 to n=6

(c) n=6 to n=2

(d) n=2 to n=1

(v) The ratio of minimum to maximum wavelength in Balmer series is

(a) 5 : 9

(b) 5 : 36

(c) 1 : 4

(d) 3 : 4