Atoms Test - 76...

The ratio of the radii of the electron orbits for the first excited state to the ground state for the hydrogen atom is:

The wave number of first line of Balmer series of hydrogen atom is $$15200\ cm^{-1}$$. What is the wave number of first line of Balmer series of $$Li^{2+}$$ ion.

In a Bohr atom the electron is replaced by a particle of mass 150 times the mass of the electron an the same charge, If $$a_0$$ is the radius of the first Bohr orbit of the orbital atom, then that of the new atom will be 

The ionization potential of H-atom is $$13.6$$V. The H-atoms in ground state are excited by monochromic radiations of photon energy $$12.09$$ eV. Then the number of spectral lines emitted by the excited atoms will be: 

The wavelength of the first member of the Balmer series is $$656.3\ nm$$. The wavelength of the second line of the Lyman series is

A $$12.5 eV$$ electron beam is used to bombard gaseous hydrogen at room temperature. What series of spectral line will be emitted ?

The speed of sound in air is $$v$$. Both the source and observer are moving towards each other with equal speed $$u$$. The speed of wind is$$w$$ from source to observer. Then, the ratio $$(\cfrac{f}{{f}_{0}})$$ of the apparent frequency to the actual frequency is given by

In Rutherford's experiment the number of alpha particles scattered through an angle of $$60^0$$ by a silver foil is $$200$$ per minute. When the silver foil is replaced by a copper coil of the same thickness, the number of $$\alpha$$-particles scattered through an angle of $$60^0$$ per minute is -

According to Moseley's law, the ratio of the slope of graph between $$\sqrt { f } $$ and $$Z$$ for $${ k }_{ \beta  }$$ and $${ k }_{ \alpha  }$$ is

How can the brightness of the pattern on the screen of cathode ray tube be changed?