Atoms And Nuclei - Modern Physics - Physics Previous Year Questions

Highly energetic electrons are bombarded on a target of an element containing 30 neutrons. The ratio of radii of nucleus to that of Helium nucleus is \((14)^{\frac{1}{3}}\). Find

(A) Atomic number of the nucleus;

(B) the frequency of \(\mathrm{K}_{\alpha}\) line of the X-ray produced.

\(\left(\mathrm{R}=1.1 \times 10^{7} \mathrm{~m}^{-1}\right.\) and \(\left.c=3 \times 10^{8} \mathrm{~m} / \mathrm{s}\right)\)

In hydrogen-like atom $(z=11)$, $n$th line of Lyman series has wavelength A equal to the de Broglie's wavelength of electron in the level from which it originated. What is the value of $n$ ?

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In the option given below, let E denote the rest mass energy of a nucleus and n a neutron. The correct option is

The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is

Assume that the nuclear binding energy per nucleon (B/A) versus mass number (A) is as shown in the figure. Use this plot to choose the correct choice(s) given below.

The wavelength of light emitted in the visible region by He\(^+\) ions after collisions with H atoms is

The quantum number n of the state finally populated in He\(^+\) ions is :

The ratio of the kinetic energy of the \(n=2\) electron for the H atom to that of He\(^+\) ion is

A radioactive sample S₁ having activity of 5 \(\mu\)Ci has twice the number of nuclei as another sample S₂ which has an activity of 10 \(\mu\)Ci. The half lives of S₁ and S₂ can be :

The speed of the particle, that can take discrete values, is proportional to

Assume that two deuteron nuclei in the core of fusion reactor at temperature T are moving towards each other, each with kinetic energy 1.5 kT, when the separation between them is large enough to neglect Coulomb potential energy. Also neglect any interaction from other particles in the core. The minimum temperature T required for them to reach a separation of 4 \(\times\) 10\(^{-15}\) m is in the range

Results of calculations for four different designs of a fusion reactor using D-D reaction are given below. Which of these is most promising based on Lawson criterion?

In the core of nuclear fusion reactor, the gas becomes plasma because of

To determine the half-life of a radioactive element, a student plots a graph of \(\ln \left| {{{dN(t)} \over {dt}}} \right|\) versus t. Here, \({{dN(t)} \over {dt}}\) is the rate of radioactive decay at time t. If the number of radioactive nuclei of this element decreases by a factor of p after 4.16 years, the value of p is __________.

It is found that the excitation frequency from ground to the first excited state of rotation for the CO molecule is close to \({4 \over \pi } \times {10^{11}}\) Hz. Then, the moment of inertia of CO molecule about its centre of mass is close to (Take h = 2\(\pi\) \(\times\) 10^\(-\)34 J-s)

A diatomic molecule has moment of inertia I. By Bohr's quantization condition, its rotational energy in the nth level (n = 0 is not allowed) is

In a CO molecule, the distance between C (mass = 12 amu) and O (mass = 16 amu), where 1 amu \(= {5 \over 3} \times {10^{ - 27}}\) kg, is close to :

The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 \(\mathop A\limits^o\). The wavelength of the second spectral line in the Balmer series of singly-ionized helium atom is

If the anti-neutrino had a mass of 3 eV/c² (where c is the speed of light) instead of zero mass, what should be the range of the kinetic energy, K, of the electron?