JEE Main > Atoms and Nuclei

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

At absolute zero, Si acts as

At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit
{tex} \begin{array} { l l } { \text { (i) electrons } } & { \text { (ii) protons } } \\ { \text { (iii) } \mathrm { He } ^ { 2 + } } & { \text { (iv) neutrons } } \end{array} {/tex}
The emission at instant can be

Sodium and copper have work functions 2.3{tex} \mathrm { eV } {/tex} and 4.5{tex} \mathrm { eV } {/tex} respectively. Then the ratio of the wavelengths is nearest to

Formation of covalent bonds in compounds exhibits

If {tex} N _ { 0 } {/tex} is the original mass of the substance of half-life period {tex} t _ { 1 / 2 } = 5 {/tex} years, then the amount of substance left after 15 years is

By increasing the temperature, the specific resistance of a conductor and a semiconductor

The energy band gap is maximum in

The part of a transistor which is most heavily doped to produce large number of majority carriers is

Which of the following are not electromagnetic waves?

A strip of copper and another of germanium are cooled from room temperature to 80{tex} \mathrm { K } {/tex} . The resistance of

Which of the following radiations has the least wavelength?

When a {tex} {U} ^ {238} {/tex} nucleus originally at rest, decays by emitting an alpha particle having a speed '{tex} u {/tex} ', the recoil speed of the residual nucleus is

The difference in the variation of resistance with temeperature in a metal and a semiconductor arises essentially due to the difference in the

A radioactive sample at any instant has its disintegration rate 5000 disintegrations per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is

A nucleus with {tex} Z = 92 {/tex} emits the following in a sequence: {tex} \alpha , \beta ^ { - } , \beta ^ { - } \alpha , \alpha , \alpha , \alpha , \alpha , \beta ^ { - } , \beta ^ { - } , \alpha , \beta ^ { + } , \beta ^ { + } , \alpha {/tex} Then {tex} Z {/tex} of the resulting nucleus is

Two identical photocathodes receive light of frequencies {tex} f _ { 1 } {/tex} and {tex} { f _ { 2 }}{/tex} . If the velocites of the photo electrons (of mass m) coming out are respectively {tex} v _ { 1 } {/tex} and {tex} v _ { 2 } , {/tex} then

Which of the following cannot be emitted by radioactive substances during their decay?

In the nuclear fusion reaction
{tex} ^ { 2 } \mathrm { H } + _ { 1 } ^ { 3 } \mathrm { H } \rightarrow _ { 2 } ^ { 4 } \mathrm { He } + n {/tex}
given that the repulsive potential energy between the two nuclei is {tex} \sim 7.7 \times 10 ^ { - 14 } \mathrm { J } {/tex} , the temperature at which the gases must be heated to initiate the reaction is nearly {tex} \left. \text { [Boltzmann's Constant } k = 1.38 \times 10 ^ { - 23 } \mathrm { J } / \mathrm { K } \right] {/tex}

Which of the following atoms has the lowest ionization potential?

The wavelengths involved in the spectrum of deuterium {tex} ({_l } {^ 2 } { D } ){/tex} are slightly different from that of hydrogen spectrum, because

In the middle of the depletion layer of a reverse- biased {tex} p-n {/tex} junction, the

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

A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is

According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency, of the incident radiation gives as straight the whose slope