The ionisation energy of hydrogen atom is 13.6 eV, the ionisation energy of helium atom would be [1988]

(1) 13.6 eV            (2) 27.2 eV           (3) 6.8 eV            (4) 54.4 eV

If an electron in an hydrogen atom jumps from an orbit $n_i=3$ to an orbit with level $n_f=2$, the frequency of the emitted radiation is 

(1) $v=\frac{36 C}{5 R}$               (2) v = $\frac{CR}{6}$                (3) v = $\frac{5 RC}{36}$             (4) v  = $\frac{6 C}{R}$

The longest and shortest wavelength of the Lyman series are (respectively)

1.  $1215 \stackrel{0}{\mathrm{A}}, 500 \stackrel{0}{\mathrm{A}}$

2.  $1215 \stackrel{0}{\mathrm{A}}, 912 \stackrel{0}{\mathrm{A}}$

3.  $912 \stackrel{0}{\mathrm{A}}, 500 \stackrel{0}{\mathrm{A}}$

4. $912 \stackrel{0}{\mathrm{A}}, 700 \stackrel{0}{\mathrm{A}}$

The shortest wavelength of Balmer series is about 

1.  912$\stackrel{\mathrm{o}}{\mathrm{A}}$

2.  121$\stackrel{\mathrm{o}}{\mathrm{A}}$

3.  3648$\stackrel{\mathrm{o}}{\mathrm{A}}$

4.  4864$\stackrel{\mathrm{o}}{\mathrm{A}}$

Which of the following transition in a hydrogen atom will produce radiations of minimum wavelength?

1.  n = 2 to n = 1

2.  n = 5 to n = 3

3.  n = 10 to n = 5

4.  n = 10 to n = 3

The frequency Of radiation emitted during the transition of an electron from a second excited state to a first excited state in H-atom is ${\mathrm{f}}_0.$ The frequency of the same transition emitted by a singly ionized He ion is

1.  $2{\mathrm{f}}_0$

2.  $4{\mathrm{f}}_0$

3.  $\frac{{\mathrm{f}}_0}{2}$

4.  $\frac{{\mathrm{f}}_0}{4}$

When neutron moving with Kinetic Energy 2eV collides with 

stationary $H_1^1$ in the ground state, the collision will be:

1.  Must be elastic

2.  may be inelastic

3.  Both

4.  Must be perfectly inelastic

If an electron in a hydrogen atom jumps from the 3rd orbit, to the 2nd orbit, it emits a photon of wavelength $\lambda$. When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be

(1) $\frac{16}{25}\lambda$               

(2) $\frac{9}{16}\lambda$

(3) $\frac{20}{7}\lambda$               

(4) $\frac{20}{13}\lambda$

Whose atomic model describes electrons being embedded in a gel of positive charge?

The ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is

(1)5/27

(2)3/23

(3)7/29

(4)9/31