Line Spectra

Q. As the wavelength decreases, the lines in spectrum appear closer together and are weaker in intensity.

1. True
2. False

Q. The wavelength of the first spectral line in the Balmer series of hydrogen atom is $6561\stackrel{\circ }{A}$. The wavelength of the second spectral line in the Balmer series of singly-ionized helium atom is

1. $1215\stackrel{\circ }{A}$
2. $1640\stackrel{\circ }{A}$
3. $2430\stackrel{\circ }{A}$
4. $4687\stackrel{\circ }{A}$

Q. The $K_{\propto }$ X - ray emission line of tungsten occurs at $\lambda$ = 0.021nm. The energy difference between K and L levels in this atom is about

1. 0.51 MeV
2. 1.2 MeV
3. 59 keV
4. 136 eV

Q. As the wavelength decreases, the lines in spectrum appear closer together and are weaker in intensity.

1. True
2. False

Q. Balmer series was observed and analysed for hydrogen before other series. A possible reason for this is

1. because it was relatively difficult to observe balmer series
2. because balmer series emissions were slowest & can be trapped for analysis
3. because balmer were of ultraviolet region
4. because balmer emissions of hydrogen were in visible range

Q. Which series of line spectrum of H-atom is observed usually in both emission and absorption spectrum?

1. Balmer
2. Brackett
3. Lyman
4. Paschen

Q. The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is

1. $2:1$
2. $1:2$
3. $4:1$
4. $2:6$