Atoms practice · Medium

If ${f_1},{f_2}$ and ${f_3}$ are the frequencies of corresponding ${K_\alpha },{K_\beta }$ and ${L_\alpha }X$-rays of an element, then

Solid targets of different elements are bombarded by highly energetic electron beams. The frequency $\left( f \right)$ of the characteristic X-rays emitted from different targets varies with atomic number $Z$ as

If the wavelength of the first line of the Lyman series for the hydrogen atom is $1210\mathop {\text{A}}\limits^ \circ$, then what will be the wavelength of the first line of the Balmer series of the hydrogen spectrum?

Which energy state of the triply ionized beryllium has the same electron orbital radius as that of ground state of hydrogen? Given $Z$ for $\mathrm{Be}\,\mathrm{ = }\,\mathrm{4}$

The shortest wave length of the spectral line (series limit) of Paschen series is

Consider the following statements.
A. Atoms of each element emit characteristics spectrum.
B. According to Bohr’s postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit
C. The density of nuclear matter depends on the size of the nucleus
D. A free neutron is stable but a free proton decay is possible
E. Radioactivity is an indication of the instability of nuclei
Choose the correct answer from the options given below.

The Rydberg constant $R$ for hydrogen is

If an electron drops from $4^{\text {th }}$ orbit to $2^{\text {nd }}$ orbit in an ${H}$-atom, then

Statement-I: An electron in hydrogen atom passes fromn $=4$ to $n=1$ level. The maximum number of photons that can be emitted is 6.

Statement-II: maximum number of photons omitted can only be 4.

$X$-rays are known to be electromagnetic radiations. Therefore the $X$-ray photon has

Which one of the series of hydrogen spectrum is in the visible region

The energy of an electron in the $n^{th}$ orbit is given by $E_n=-13.6 / n^2 \mathrm{eV}$. Calculate the energy required to excite an electron from ground state to the second excited state.

How may different wavelengths be observed in the spectrum from a hydrogen sample if atoms are excited to states with quantum number (n)?

Which of the following is true?

X-rays are used in determining the molecular structure of crystalline because its

An $\alpha$-particle after passing through a potential difference of $V$ volts collides with a nucleus. If the atomic number of the nucleus is ${Z}$ then the distance of closest approach of $\alpha$-particle to the nucleus will be

Statement-I: In the experiment of alpha particle scattering, extremely thin gold foils are preferred over other metals.

Statement-II: Gold is a ductile material.

The longest wavelength emitted in hydrogen atom belonging to Balmer series, is

Assertion: When light is passed through a sample of hydrogen atoms in ground state, then wavelengths of absorption lines are same as wavelengths of lines of Lyman series in emission spectrum. and

Reason : In ground state hydrogen atom will absorb only those radiation which will excite to higher energy level.

Assertion: The Balmer series lies in the visible region of the electromagnetic spectrum.

Reason : $\frac{1}{\lambda}=\mathrm{R}\left(\frac{1}{2^2}-\frac{1}{\mathrm{n}^2}\right)$, where, $\mathrm{n}=3,4,5, \ldots$

An $\alpha$-particle of energy $4\,\mathrm{MeV}$ is scattered by gold foil $(Z=79)$. Calculate the maximum volume in which positive charge of the atom is likely to be concentrated.

Which of the following is true for number of spectral lines in going from Lyman series to $P$-fund series

In Davisson - Germer experiment maximum intensity is observed at

Mosley’s law relates the frequencies of line $X$-rays with the following characteristics of the target element

Which of the following statements are true regarding Bohr’s model of hydrogen atom

(I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus

(II) Radii of allowed orbits of electron are proportional to the principal quantum number

(III) Frequency with which electrons orbit around the nucleus is discrete orbits is inversely proportional to the cube of principal quantum number

(IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits

Select correct answer using the codes given below

X-ray of wavelength $\lambda = 2\mathop A\limits^ \circ$ is emitted from the metal target. The potential difference applied across the cathode and the metal target is

In an ionisation experiment it is found that a doubly ionised particle enters a magnetic field of 1 T and moves in a circular path of radius 1 m with a speed of $1.6 \times {10^7}\;\mathrm{m}{\mathrm{s}^{ - 1}}$. The particle must be

Energy of electron in an orbit of $H$-atom is

In Davisson and Germer experiment intensity of scattered beam of electron was maximum at $50^{\circ}$ scattering angle and at

In the Bohr model of hydrogen atom, the electron is treated as a particle going in a circle with the centre at the proton. The proton itself is assumed to be fixed in an inertial frame. The centripetal force is provided by the Coloumb attraction. In the ground state, the electron goes round the proton in a circle of radius $5.3 \times 10^{-11} \mathrm{~m}$. Find the speed of the electron in the ground state. Mass of the electron $=9.1 \times 10^{-31} \mathrm{~kg}$ and charge of the electron $=1.6 \times 10^{-19} \mathrm{C}$.