When hydrogen atom is in its first excited level, its radius is __________ of the Bohr radius.

The energy of the ground state of hydrogen is -13.6 eV. The energy of the first excited state is _____________.

According to to Bohr, the relation between principal quantum number (n) and radius of the orbit (r) is _____________.

The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to _____________.

The fig. represents the observed intensity of X-rays emitted by an X-ray tube as a function of wavelength. The sharp peaks A and B denote ____________.
 

An a-particle of energy 10 meV is scattered through 180^o by a fixed uranium nucleus. The distance of the closest approach is of the order of _____________.

Millikan's oil drop experiment established that is ____________.

An oil drop carrying a charge q has a mass of m kg. It is falling freely in the air with terminal speed v. The electric field required to make the drop move upwards with the same speed is ______________.

An alpha nucleus of energy 1/2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of the closest approach for the alpha nucleus will be proportional to ____________.

The total energy of electrons in the ground state of a hydrogen atom is -13.6 eV. The k.E of an electron in the first excited state is ____________.

The ionization energy of hydrogen atom is -13.6e V. The energy corresponding to a transition between 3rd and 4th orbit is ______________.

In terms of Bohr radius a₀, the radius of the third Bohr orbit of a hydrogen atom is given by ______________.

The ground state energy of a hydrogen atom is 13.6 eV. The energy needed to ionize H₂ atom from its second excited state ______________.

The circumference of an electron's orbit of radius r must be an integral multiple of de Broglie wavelength that is ________________.

Bohr's postulate is based on _______________.