Question 1 :
The ratio of specific charge of an {tex} \alpha {/tex} -particle to that of a proton is

Question 2 :
The ratio of the energy of a photon with {tex} \lambda = 150\ { nm } {/tex} to that with {tex} \lambda = 300 \mathrm { nm } {/tex} is

Question 4 :
The energy of a photon is {tex} E = h v {/tex} and the momentum of photon {tex} p = \frac { h } { \lambda } , {/tex} then the velocity of photon will be

Question 7 :
If the binding energy of the electron in a hydrogen atom is 13.6{tex} \mathrm { eV } {/tex} , the energy required to remove the electron from the first excited state of {tex} \mathrm { Li } ^ { + + } {/tex} is

Question 8 :
Hydrogen atom is excited from ground state to another state with principal quantum number equal to {tex} 4 . {/tex} Then the number of spectral lines in the emission spectra will be:

Question 9 :
An electron is accelerated through a p.d. of {tex} 45.5 {/tex} volt. The velocity acquired by it is (in {tex} \mathrm { ms } ) {/tex}

Question 11 :
The radius of the Bohr orbit in the ground state of hydrogen atom is 0.5 Å The radius of the orbit of the electron in the third excited state of He⁺ will be -

Question 12 :
Suppose an electron is attracted towards the origin by a force {tex} k / r {/tex} where {tex} k {/tex} is a constant and {tex} r {/tex} is the distance of the electron from the origin. By applying Bohr model to this system, the radius of the {tex} n ^ { \text {th } } {/tex} orbital of the electron is found to be {tex} r _ { n } {/tex} and the kinetic energy of the electron to be {tex} T _ { n } {/tex}. Then which of the following is true?

Question 13 :
If the rest mass of electron or positron is 0.51 MeV, then the kinetic energy of each particle in the electron-positron pair production by a γ-photon of 2.42 MeV will be -

Question 14 :
The electron in a hydrogen atom makes a transition from n = n₁ to n = n₂ state. The time period of the electron in the initial state (n₁) is eight times that in final state (n₂). The possible values of n₁ and n₂ are-

Question 15 :
Hydrogen atom in its ground state is excited by radiation of wavelength 975 Å. How many lines will be there in the emission spectrum

Question 17 :
If proton and {tex} \alpha {/tex} -particles are accelerated by the same potential difference, then their De-Broglie wavelength will be in the ratio of

Question 18 :
The de-Broglie wavelength of a particle moving with a velocity {tex} 2.25 \times 10 ^ { 8 } \mathrm { m } / \mathrm { s } {/tex} is equal to the wavelength of photon. The ratio of kinetic energy of the particle to the energy of the photon is (velocity of light is {tex} 3 \times 10 ^ { 8 } \mathrm { m } / \mathrm { s } ) {/tex}

Question 19 :
In certain element the <em>K-</em>shell electron energy is – 18.525 keV and the <em>L-</em>shell electron energy is – 3 keV. When an electron jumps from the <em>L</em>-shell to <em>K</em> shell, an X-ray photon is emitted. The wavelength of the emitted <em>X</em>-rays is

Question 20 :
The wave number of the series limit of Lyman series is-