In the following atoms and moleculates for the transition from n= 2 to n = 1, the spectral line of minimum wavelength will be produced by 
(1) Hydrogen atom               

(2) Deuterium atom

(3) Uni-ionized helium           

(4) di-ionized lithium

Which one of the series of hydrogen spectrum is in the visible region 

1. Lyman series             

2. Balmer series

3. Paschen series           

4. Bracket series

If the wavelength of the first line of the Balmer series of hydrogen is 6561 $\stackrel{0}{\mathrm{A}}$, the wavelength of the second line of the series should be 
(a) 13122 $\stackrel{0}{\mathrm{A}}$                  (b) 3280 $\stackrel{0}{\mathrm{A}}$
(c) 4860 $\stackrel{0}{\mathrm{A}}$                    (d) 2187 $\stackrel{0}{\mathrm{A}}$

The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the

(a) Balmer series                 (b) Pfund series
(c) Paschen series                (d) Lyman series

In terms of Rydberg's constant R, the wave number of the first Balmer line is 
(1) R               

(2) 3R

(3) $\frac{5\mathrm{R}}{36}$         

(4) $\frac{8\mathrm{R}}{9}$

In Bohr's model of hydrogen atom, let PE represents potential energy and TE the total energy. In going to a higher level 

(1) PE decreases, TE increases

(2) PE increases, TE increases

(3) PE decreases, TE decreases

(4) PE increases, TE decreases

An ionic atom equivalent to hydrogen atom has wavelength equal to 1/4 of the wavelengths of hydrogen lines. The ion will be 
(1) ${\mathrm{He}}^{+}$        

(2) ${\mathrm{Li}}^{++}$

(3) ${\mathrm{Ne}}^{9+}$       

(4) ${\mathrm{Na}}^{10+}$

To explain his theory, Bohr used

(a) Conservation of linear momentum

(b) Conservation of angular momentum

(c) Conservation of quantum frequency

(d) Conservation of energy

Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be 
(a) 3                   (b) 6
(c) 5                   (d) 2