The ionisation potential of hydrogen atom is

1. 13.60 volt

2. 8.24 volt

3. 10.36 volt 

4. 14.24 bolt

Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emitted by hydrogen will be:

1. two 

2. three

3. four 

4. one

Consider the spectral line resulting from transition \(n=2\) to \(n = 1\) in the atoms and ions given below.  The shortest wavelength is given by:

An $\alpha -$particle of energy 5 MeV is scattered through $180°$ by a fixed uranium nucleus. The distance of closest approach is of the order

1. ${10}^{-10}<mspace\; width="1em"></mspace>m$ 

2. ${10}^{-13}<mspace\; width="1em"></mspace>m$ 

3. ${10}^{-14}<mspace\; width="1em"></mspace>m$ 

4. ${10}^{-16}<mspace\; width="1em"></mspace>m$

The wavelength of K_a X-rays produced by an X-ray tube is 0.76 $\stackrel{\circ }{A}$. Find the atomic number of the anode material of the tube?

1. 41

2. 30

3. 20

4. 10

Energy levels A, B, C of a certain atom correspond to increasing values of energy i.e. $E_A<E_B<E_C.$ If ${\lambda }_1,<mspace\; width="1em"></mspace>{\lambda }_2,<mspace\; width="1em"></mspace>{\lambda }_3$ are the wavelengths of the radiation corresponding to the transitions C to B, B to A and C to A respectively, which of the following relation is correct?

1. ${\lambda }_3={\lambda }_1+{\lambda }_2$ 

2. ${\lambda }_3=\frac{{\lambda }_1{\lambda }_2}{{\lambda }_1+{\lambda }_2}$

3. ${\lambda }_1+{\lambda }_2+{\lambda }_3=0$ 

4. ${\lambda }_3^2={\lambda }_1^2+{\lambda }_2^2$

The velocity of the electron in the ground state (H - atom) is 

1. $2.18\times {10}^5<mspace\; width="1em"></mspace>m/s$   

2. $2.18\times {10}^6<mspace\; width="1em"></mspace>m/s$

3. $2.18\times {10}^7<mspace\; width="1em"></mspace>m/s$   

4. $2.18\times {10}^8<mspace\; width="1em"></mspace>m/s$

Atoms have different atomic numbers as well as different mass numbers but have the same number of neutrons is called:

Which of the following transitions gives photon of maximum energy?

1. n = 1 to n = 2 

2. n = 2 to n = 1

3. n = 2 to n = 6 

4. n = 6 to n = 2