Atoms practice · Medium

An X-ray tube with a copper target is found to be emitting lines other than those due to copper. The $K_\alpha$ line of copper is known to have a wavelength $1.5405 \mathop {\text{A}}\limits^ \circ$ and the other two $K_\alpha$ lines observed have wavelengths $0.7090 \mathop {\text{A}}\limits^ \circ$ and $1.6578 \mathop {\text{A}}\limits^ \circ$. Identify the impurities.

Assertion (A): Between any two given energy levels, the number of absorption transitions is always less than or equal to the number of emission transitions.

Reason (R): Absorption transitions start from the lowest energy level only and may end at any higher energy level. But emission trasitions may start from any higher energy level and end at an energy level below it.

The wavelength of radiation emitted is ${\lambda _0}$ when an electron jumps from the third to second orbit of hydrogen atom. For the electron jump from fourth to the second orbit of the hydrogen atom, the wavelength of radiation emitted will be

Assertion: Bohr's atomic model can be applied for every atom.

Reason: The energy state of election in atom is continuous.

The energy required to remove one of the electrons from a neutral helium atom is 24.6 eV. The energy required to remove both the electrons from a neutral helium atom is

Consider a hydrogen like atom in Bohr's model. It is given that difference between $(n+1)^{\text {th}}$ Bohr's radius and $n^{\text {th}}$ Bohr's radius is equal to $(n-1)^{\text {th}}$ Bohr's radius, then the energy of $n^{\text {th}}$ state (in $\mathrm{eV}$) is [${Z}=$ atomic number]

In the above figure $D$ and $E$ respectively represent

If scattering particles are $\mathrm{56}$ for ${90^\circ }$ angle, then at an angle ${60^\circ }$ it will be

The angular momentum of an electron in the first orbit of ${Li}^{++}$ion is

Assertion (A): In a metal all the free electrons have same energy.

Reason (R): Electrons do not obey Pauli's exclusive principle.

The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true

The voltage applied across an X-ray tube is nearly equal to

In Bohr’s atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level:

An electron in the hydrogen atom jumps excited state $n$ to the ground state. The wavelength so emitted illuminates a photosensitive material having work function $2.75\;eV.$ If the stopping potential of the photoelectron is $10\;eV,$ then the value of $n$ is

Davisson and Germer experiment proved

Consider Bohr's atomic theory of single electron system, where the transition of electron from fourth excited state to second excited state of Lithium emits radiation which knocks out the electron from fourth excited state of an atom of an element. The atomic number of the element is

In the lowest energy level of hydrogen atom, the electron has the angular momentum

Which of the following statements about the Bohr model of the hydrogen atom is false

X-rays and $\gamma$-rays of the same energies may be distinguished by

In the hydrogen atom, an electron makes a transition from $\mathrm{n}=2$ to $\mathrm{n}=1$. The magnetic field produced by the circulating electron at the nucleus

In radio therapy, $X$-rays are used to

The angular momentum of an electron in hydrogen atom is $\frac{5 h}{2 \pi}$. Here $h$ is the Plank's constant. The potential energy of this electron is

In Bohr’s model of hydrogen atom, which of the following represents the variation of nth orbit radius with n?

The Bohr model of atoms

Whenever a hydrogen atom emits a photon in the Balmer series

An ionised ${H}$-molecule consist of an electron and two protons. One proton are separated by a small distance of the order of angstrom. In the ground state

An electron in the $n = 1$ orbit of hydrogen atom is bounded by $13.6\,\,eV$. Energy requires to ionize it is

The wavelength of X-rays is of the order of

For the structural analysis of crystals, $X$-rays are used because

The structure of solid crystals is investigated by using