Atoms and Nuclei

In Li^+ +, electron in first Bohr orbit is excited to a level by a radiation of wavelength $\lambda$. When the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of $\lambda$? (Given : H = 6.63 × 10^–34 Js; c = 3 × 10⁸ ms ^–1)

The mass of proton, neutron and helium nucleus are respectively $1.0073~u,1.0087~u$ and $4.0015~u$. The binding energy of helium nucleus is :

If radius of the $\matrix{ {27} \cr {13} \cr }$ $Al$ nucleus is estimated to be $3.6$ fermi then the radius of $\matrix{ {125} \cr {52} \cr } \,Te$ nucleus is estimated to be nearly

The waves emitted when a metal target is bombarded with high energy electrons are

A radioactive sample is undergoing $\alpha$ decay. At any time t₁, its activity is A and another time t₂, the activity is ${A \over 5}$. What is the average life time for the sample?

If a radioactive element having half-life of $30 \mathrm{~min}$ is undergoing beta decay, the fraction of radioactive element remains undecayed after $90 \mathrm{~min}$. will be

Given below are two statements: Statement I : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model. Statement II : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model. In the light of the above statements, choose the most appropriate from the options given below

If $13.6$ $eV$ energy is required to ionize the hydrogen atom, then the energy required to remove an electron from $n=2$ is

The wavelengths involved in the spectrum of deuterium $\left( {{}_1^2\,D} \right)$ are slightly different from that of hydrogen spectrum, because

Which of the following atoms has the lowest ionization potential ?

If the binding energy of the electron in a hydrogen atom is $13.6eV,$ the energy required to remove the electron from the first excited state of $L{i^{ + + }}$ is

A He⁺ ion is in its first excited state. Its ionization energy is :-

Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2nd Balmer line (n = 4 to n = 2) will be :

The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5^th excited state of a hydrogen atom is :

If the binding energy per nucleon in ${}_3^7Li$ and ${}_2^4He$ nuclei are $5.60$ $MeV$ and $7.06$ $MeV$ respectively, then in the reaction $p + {}_3^7Li \to 2\,{}_2^4He$ energy of proton must be

Imagine that a reactor converts all given mass into energy and that it operates at a power level of 10⁹ watt. The mass of the fuel consumed per hour in the reactor will be : (velocity of light, c is 3×10⁸ m/s)

Choose the correct option from the following options given below :

An alpha nucleus of energy ${1 \over 2}m{v^2}$ bombards a heavy nuclear target of charge $Ze$. Then the distance of closest approach for the alpha nucleus will be proportional to

The radiation corresponding to $3 \to 2$ transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field $3 \times {10^{ - 4}}\,T.$ If the radius of the larger circular path followed by these electrons is $10.0$ $mm$, the work function of the metal is close to: