Energy of an electron in an excited hydrogen atom is – 3.4 eV. Its angular momentum will be:
h = $6.626\times {10}^{-34} \mathrm{J}-\mathrm{s}$

(1) $1.11\times {10}^{-34} \mathrm{J} \sec$       

(2) $1.51\times {10}^{-31} \mathrm{J} \sec$

(3) $2.11\times {10}^{-34} \mathrm{J} \sec$       

(4) $3.72\times {10}^{-34 }\mathrm{J} \sec$

The wavelength of light emitted when an electron jumps from second orbit to first orbits in a hydrogen atom is 
(a) $1.215\times {10}^{-7} \mathrm{m}$         (b) $1.215\times {10}^{-5} \mathrm{m}$
(c) $1.215\times {10}^{-4} \mathrm{m}$          (d) $1.215\times {10}^{-3} \mathrm{m}$

Energy of the electron in nth orbit of hydrogen atom is given by ${\mathrm{E}}_{\mathrm{n}}=-\frac{13.6}{{\mathrm{n}}^2}\mathrm{eV}$. The amount of energy needed to transfer electron from first orbit to third orbit is

(1) 13.6 eV             

(2) 3.4 eV

(3) 12.09 eV           

(4) 1.51 eV

The de-Broglie wavelength of an electron in the first Bohr orbit is 

(1) Equal to one fourth the circumference of the first orbit

(2) Equal to half the circumference of the first orbit

(3) Equal to twice the circumference of the first orbit

(4) Equal to the circumference of the first orbit

An electron changes its position from orbit n = 4 to the orbit n = 2 of an atom. The wavelength of the emitted radiation’s is (R = Rydberg’s constant)

(1) $\frac{16}{\mathrm{R}}$             

(2) $\frac{16}{3\mathrm{R}}$

(3) $\frac{16}{5\mathrm{R}}$             

(4) $\frac{16}{7\mathrm{R}}$

What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit

(1) 27 : 25               

(2) 20 : 27

(3) 20 : 25               

(4) 25 : 27

The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state

1. 0 eV                       

2. – 27.2 eV

3. 1 eV                       

4. 2 eV

The magnetic moment $\left(\mathrm{\mu }\right)$ of a revolving electron around the nucleus varies with principal quantum number n as

(1) $\mathrm{\mu }\propto \mathrm{n}$            

(2) $\mathrm{\mu }\propto 1/\mathrm{n}$

(3) $\mathrm{\mu }\propto {\mathrm{n}}^2$           

(4) $\mathrm{\mu }\propto 1/{\mathrm{n}}^2$

In hydrogen-like atoms, the ratio of difference of energies ${\mathrm{E}}_{4\mathrm{n}} - {\mathrm{E}}_{2\mathrm{n}} \mathrm{and} {\mathrm{E}}_{2\mathrm{n}} - {\mathrm{E}}_{\mathrm{n}}$ varies with atomic number z and principal quantum number n as

1. $\frac{{\mathrm{z}}^2}{{\mathrm{n}}^2}$

2. $\frac{{\mathrm{z}}^4}{{\mathrm{n}}^4}$

3. z/n

4. none of these

A hydrogen atom is in an excited state of principal quantum number n. It emits a photon of wavelength $\mathrm{\lambda }$ when returns to the ground state. The value of n is (R = Rydberg constant)

1. $\sqrt{\mathrm{\lambda R}\left(\mathrm{\lambda R} - 1\right)}$

2. $\sqrt{\frac{\left(\mathrm{\lambda R} - 1\right)}{\mathrm{\lambda R}}}$

3. $\sqrt{\frac{\mathrm{\lambda R}}{\left(\mathrm{\lambda R} - 1\right)}}$

4. $\sqrt{\left(\mathrm{\lambda R} - 1\right)}$