Atoms and Nuclei PYQs - Last 10 Years

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Practice 159 MHT CET Physics questions from Atoms and Nuclei. Use the year-wise and type-wise breakdown to prioritize recent PYQs, then continue into the question list below.

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Last 10 Years Atoms and Nuclei Questions

Showing 50 of 159 filtered questions.

1Atoms And Nuclei

The angular momentum of an electron in Bohr's hydrogen atom having energy $(-0.544)$ eV is($h$ = Planck's constant)

2Atoms And Nuclei

An electron in the hydrogen atom jumps from $n^{th}$ energy state to the ground state. The wavelength so emitted illuminates a photosensitive material having work function $2.65$ eV. If the maximum kinetic energy of the emitted photoelectro...

3Atoms And Nuclei

Activity of a radioactive sample decreases to $\left(\dfrac{1}{4}\right)^{th}$ of its original value in 4 days. Then in 16 days its activity will become $x$ times the original value. The value of $x$ is

4Atoms And Nuclei

Which of the following is an integral multiple of $\dfrac{h}{2\pi}$ in Bohr's model of an hydrogen atom?

5Atoms And Nuclei

The kinetic energy of the electron in an orbit of radius $r$ in hydrogen atom is proportional to ($e$ = electronic charge)

6Atoms And Nuclei

A radioactive sample has half-life of $5$ years. The percentage of fraction decayed in $10$ years will be

7Atoms And Nuclei

The shortest wavelength in the Balmer series of hydrogen atom is equal to the shortest wavelength in the Brackett series of a hydrogen like atom of atomic number 'Z'. The value of 'Z' is

8Atoms And Nuclei

A radioactive element has rate of disintegration $16{,}000$ disintegrations per minute at a particular instant. After four minutes, it becomes $2000$ disintegrations per minute. The decay constant per minute is

9Atoms And Nuclei

The magnetic moment of electron due to orbital motion is proportional to($n$ = principal quantum number)

10Atoms And Nuclei

The de-Broglie wavelength of an electron moving in the $n^{th}$ Bohr orbit of radius 'r' is

11Atoms And Nuclei

If the ionisation energy for the hydrogen atom is $13.6$ eV, then the energy required to excite it from the ground state to the next higher state is nearly

12Atoms And Nuclei

The angular momentum of the electron in the third Bohr orbit of a hydrogen atom is '$l$' so its angular momentum in the fourth Bohr orbit is

13Atoms And Nuclei

The triply ionized beryllium ($\text{Be}^{+++}$) has the same electron orbital radius as that of the ground state of hydrogen. Hence, the energy state of triply ionized beryllium is (Given $Z = 4$ for beryllium)

14Atoms And Nuclei

Two samples A and B contain equal amount of radioactive substances. If $\left(\dfrac{1}{8}\right)^{th}$ of sample A and $\left(\dfrac{1}{128}\right)^{th}$ of sample B, remain after 9 hours, then the ratio of half life period of B to that of...

15Atoms And Nuclei

If the difference between $(n + 1)^{th}$ Bohr radius and $n^{th}$ Bohr radius is given by $(n - 1)^{th}$ Bohr radius, then the value of n is

16Atoms And Nuclei

The de Broglie wavelength of the electron in the ground state is $\lambda_1$ and that in the $n = 3$ level is $\lambda_3$ then $\lambda_3$ is given by

17Atoms And Nuclei

The half-life of the isotope ${}_{11}\text{Na}^{24}$ is 15 hr. How much time does it take for $\left(\dfrac{7}{8}\right)^{\text{th}}$ of a sample of this isotope to decay ?

18Atoms And Nuclei

The orbital magnetic moment $(m_{orb})$ of a revolving electron around the nucleus varies with the principal quantum number ($n$) as

19Atoms And Nuclei

For wavelength of visible radiation of Hydrogen spectrum, Balmer gave an equation as $\lambda = \dfrac{xm^2}{m^2-4}$, where m is the integer value. The value of x in terms of Rydberg's constant R is

20Atoms And Nuclei

The activity of a radioactive sample is measured as $N_0$ counts per minute at time $t = 0$ and $\dfrac{N_0}{e}$ counts per minute at time $t = 3$ minute. The time (in minute) in which the activity reduces to half the value, is

21Atoms And Nuclei

In Bohr's atomic model, the energy of the electron is 'E' in the second orbit of hydrogen atom. So the energy of the electron in the third orbit of helium atom $(Z = 2)$ will be

22Atoms And Nuclei

Using Bohr's atomic model, the orbital period of electron in hydrogen atom in the $n^{\text{th}}$ orbit is ($\epsilon_0$=permittivity of free space, h=Planck's constant, m = mass of electron, e = electronic charge)

23Atoms And Nuclei

The force acting on the electron in hydrogen atom (Bohr's theory) is related to the principal quantum number n as

24Atoms And Nuclei

The ratio of the density of oxygen nucleus $({}^{16}_{8}\text{O})$ and helium nucleus $({}^{4}_{2}\text{He})$ is

25Atoms And Nuclei

An electron makes a transition from an excited state to the ground state of a hydrogen like atom. Out of the following statements which one is correct ?(A) K.E, P. E. and T.E. decreases(B) K.E. increases but P. E. and T.E. decreases(C) K.E....

26Atoms And Nuclei

Two different radioactive elements with half lives $T_1$ and $T_2$ have undecayed atoms $N_1$ and $N_2$ respectively, present at a given instant. The ratio of their activities at this instant is

27Atoms And Nuclei

If 'E' and 'L' denote the magnitude of total energy and angular momentum of revolving electron in $n^{th}$ Bohr orbit then

28Atoms And Nuclei

When the electron orbiting in hydrogen atom in its ground state moves to the third excited state, the de-Broglie wavelength associated with it

29Atoms And Nuclei

In the hydrogen atom, radii of the first four Bohr orbits are related as

30Atoms And Nuclei

The electron in hydrogen atom is initially in the second excited state. When it finally moves to ground state, the maximum number of spectral lines emitted are

31Atoms And Nuclei

An electron is revolving in a circular orbit of radius 'r' in hydrogen atom. Using Bohr's theory, the angular momentum of the electron is(M = magnetic dipole moment, m = mass of electron)

32Atoms And Nuclei

The ratio of centripetal acceleration for an electron revolving in 3rd and 5th Bohr orbit of hydrogen atom is

33Atoms And Nuclei

For hydrogen atom, $\lambda_1$ and $\lambda_2$ are the wavelengths corresponding to the transitions $1$ and $2$ respectively as shown in figure. The ratio of $\lambda_1$ and $\lambda_2$ is $x/32$. The value of $x$ is

34Atoms And Nuclei

The wavelength of the radiation emitted is $\lambda_0$ when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen ...

35Atoms And Nuclei

The number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is ($h$ = Planck's constant, $m$ is the mass of electron and $r$ is the radius of the orbit.)

36Atoms And Nuclei

The kinetic energy of the electron in an orbit of radius $r$ in hydrogen atom is proportional to ($e$ = electronic charge)

37Atoms And Nuclei

In Bohr's theory of hydrogen atom, 'r' is the radius of the orbit, 'V' is the speed of electron and E is the total energy of the electron. Out of the following which physical quantity is inversely proportional to principal quantum number?

38Atoms And Nuclei

Bohr model is applied to a particle of mass 'm' and charge 'q' moving in a plane under the influence of a transverse magnetic field B. The energy of the charged particle in the $n^{th}$ level will be (h=Planck's constant)

39Atoms And Nuclei

The ratio of the total energy of the $2^{\text {nd }}$ orbit electron for the hydrogen atom ($^1\mathrm{H}$) to that of a helium ion ($\mathrm{He}^+$) is :

40Atoms And Nuclei

A radioactive element having half-life 30 min . is undergoing beta decay. The fraction of radioactive element remains undecayed after 90 min . will be

41Atoms And Nuclei

The ratio of energies of photons produced due to transition of electron of hydrogen atom from its (i) third to $2^{\text {nd }}$ energy level and (ii) highest energy level to $3^{\text {rd }}$ level is

42Atoms And Nuclei

In Paschen series, wavelength of first line is ' $\lambda_1$ ' and for Brackett series, wavelength of first line is ' $\lambda_2$ ' then ratio $\frac{\lambda_1}{\lambda_2}$ is

43Atoms And Nuclei

The magnetic moment of electron due to orbital motion is proportional to ( $\mathrm{n}=$ principal quantum number)

44Atoms And Nuclei

The frequencies for series limit of Balmer and Paschen series are ' $\mathrm{V}_1$ ' and ' $\mathrm{V}_3$ ' respectively. If frequency of first line of Balmer series ' $\mathrm{V}_2$ ' then the relation between $V_1, V_2$ and $V_3$ is

45Atoms And Nuclei

A radio active element has rate of disintegration 8000 disintegrations per minute at a particular instant. After four minutes it becomes 2000 disintegrations per minute. The decay constant per minute is

46Atoms And Nuclei

A radioactive element has rate of disintegration 9000 disintegration per minute at a particular instant. After two minutes it becomes 3000 disintegration per minute. The decay constant per minute is

47Atoms And Nuclei

In hydrogen atom in its ground state, the first Bohr orbit has radius ' $\mathrm{r}_1$ '. When the atom is raised to one of its excited states, the electrons orbital velocity becomes one-third. The radius of that orbit is

48Atoms And Nuclei

The activity of radioactive sample is measured as $\mathrm{N}_0$ counts per minute at time $\mathrm{t}=0$, and $\frac{\mathrm{N}_0}{\mathrm{e}}$ counts per minute at time $\mathrm{t}=3$ minute, The activity reduces to half its value in time...

49Atoms And Nuclei

In hydrogen atom, the energy of electron in first and third orbit is ' $E_1$ ' and' $E_3$ ' respectively. If $E_3=x E_1$ then the value of $x$ will be

50Atoms And Nuclei

A radioactive element ${ }_{92}^{242} \mathrm{X}$ emits two $\alpha$ particles, one electron and two positrons. The product nucleus is represented by ${ }_{\mathrm{p}}^{234} \mathrm{Y}$. The value of $P$ is