Which of the transitions in hydrogen atom emits a photon of lowest frequency (n = quantum number)
(1) n = 2 to n = 1             

(2) n = 4 to n = 3

(3) n = 3 to n = 1             

(4) n = 4 to n = 2

According to Bohr's theory, the expressions for the kinetic and potential energy of an electron revolving in an orbit is given respectively by
(a)$+\frac{{\mathrm{e}}^2}{8{\mathrm{\pi \epsilon }}_0\mathrm{r}}$ and  $-\frac{{\mathrm{e}}^2}{4{\mathrm{\pi \epsilon }}_0\mathrm{r}}$            (b) $+\frac{8{\mathrm{\pi \epsilon }}_0{\mathrm{e}}^2}{\mathrm{r}}$ and $-\frac{4{\mathrm{\pi \epsilon }}_0{\mathrm{e}}^2}{\mathrm{r}}$
(c) $-\frac{{\mathrm{e}}^2}{8{\mathrm{\pi \epsilon }}_0\mathrm{r}}$ and $-\frac{{\mathrm{e}}^2}{4{\mathrm{\pi \epsilon }}_0\mathrm{r}}$            (d) $+\frac{{\mathrm{e}}^2}{8{\mathrm{\pi \epsilon }}_0\mathrm{r}}$ and $+\frac{{\mathrm{e}}^2}{4{\mathrm{\pi \epsilon }}_0\mathrm{r}}$

The absorption transitions between the first and the fourth energy states of hydrogen atom are 3. The emission transitions between these states will be 
1. 3             

2. 4

3. 5             

4. 6

The ratio of longest wavelength and the shortest wavelength observed in the five spectral series of emission spectrum of hydrogen is 
(1) $\frac{4}{3}$             

(2) $\frac{525}{376}$

(3) 25

(4) $\frac{900}{11}$

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

 According to Bohr's model, the radius of the second orbit of helium atom is 
(1) 0.53 Å             

(2) 1.06 Å

(3) 2.12 Å             

(4) 0.265 Å

The fact that photons carry energy was established by

(1) Doppler's effect               

(2) Compton's effect

(3) Bohr's theory                   

(4) Diffraction of light

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

The third line of Balmer series of an ion equivalent to hydrogen atom has wavelength of 108.5 nm. The ground state energy of an electron of this ion will be 
(1) 3.4 eV               

(2) 13.6 eV

(3) 54.4 eV             

(4) 122.4 eV

Hydrogen atom emits blue light when it changes from n = 4 energy level to the n = 2 level. Which colour of light would the atom emit when it changes from the n = 5 level to the n = 2 level 
(1) Red                   

(2) Yellow

(3) Green               

(4) Violet