Structure of Atom

The group number, number of valence electrons, and valency of an element with atomic number 15, respectively, are:

In a hydrogen atom, if energy of an electron in ground state is -13.6 eV, then that in the 2^nd excited state is

In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen

According to Bohr's theory, the angular momentum of an electron in 5^th orbit is

Ionisation energy of He⁺ is 19.6 x 10^–18 J atom^–1. The energy of the first stationary state (n = 1) of Li²⁺ is

Which of the following is the energy of a possible excited state of hydrogen?

The radius of the second Bohr orbit for hydrogen atom is: (Planck’s Const. h = 6.6262 × 10⁻³⁴ Js; mass of electron = 9.1091 × 10⁻³¹ kg; charge of electron (e) = 1.60210 × 10⁻¹⁹ C; permittivity of vacuum ($${\varepsilon _0}$$) = 8.854185 × 10⁻¹² kg⁻¹ m⁻³ A²)

The de-Broglie's wavelength of electron present in first Bohr orbit of 'H' atom is :

The radius of the second Bohr orbit, in terms of the Bohr radius, a₀, in Li²⁺ is :

The de Broglie wavelength of an electron in the 4th Bohr orbit is :

The difference between the radii of 3^rd and 4^th orbits of Li²⁺ is R₁ . The difference between the radii of 3^rd and 4^th orbits of He⁺ is $$\Delta$$R₂ . Ratio $$\Delta$$R₁ : $$\Delta$$R₂ is :

According to Bohr's atomic theory : (A) Kinetic energy of electron is $$\propto {{{Z^2}} \over {{n^2}}}$$. (B) The product of velocity (v) of electron and principal quantum number (n), $$'vn' \propto {Z^2}$$. (C) Frequency of revolution of electron in an orbit is $$\propto {{{Z^3}} \over {{n^3}}}$$. (D) Coulombic force of attraction on the electron is $$\propto {{{Z^3}} \over {{n^4}}}$$. Choose the most appropriate answer from the options given below :

Which of the following forms of hydrogen emits low energy $$\beta$$⁻ particles?

Given below are two statements : Statement I : Bohr's theory accounts for the stability and line spectrum of Li⁺ ion. Statement II : Bohr's theory was unable to explain the splitting of spectral lines in the presence of a magnetic field. In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements. Statement I : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus. Statement II : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in principal quantum number. In the light of the above statements, choose the most appropriate answer from the options given below :

If the radius of the 3^rd Bohr's orbit of hydrogen atom is r₃ and the radius of 4^th Bohr's orbit is r₄. Then :

Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Energy of $$2 \mathrm{s}$$ orbital of hydrogen atom is greater than that of $$2 \mathrm{s}$$ orbital of lithium. Reason R: Energies of the orbitals in the same subshell decrease with increase in the atomic number. In the light of the above statements, choose the correct answer from the options given below.

Identify the incorrect statement from the following.

The radius of the $$\mathrm{2^{nd}}$$ orbit of $$\mathrm{Li^{2+}}$$ is $$x$$. The expected radius of the $$\mathrm{3^{rd}}$$ orbit of $$\mathrm{Be^{3+}}$$ is