JEE Main · 2021 · 17 Mar 2021 · Shift 1 · Modern Physics

Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?

(A)6✓ Correct
(B)8
(C)4
(D)1

Answer: (A)

Solution

For a hydrogen-like species the energy of the level of principal quantum number

n

E_{n} = - 13.6 Z^{2} / n^{2}

eV. Hydrogen in its ground state has

E_{1} = - 13.6

eV, while carbon treated as a one-electron ion carries nuclear charge

Z = 6

. Setting the carbon level equal to the hydrogen ground-state energy,

- 13.6 (6^{2} / n^{2}) = - 13.6

, so

36/ n^{2} = 1

and

n^{2} = 36

, giving

n = 6

. The level of carbon that matches the hydrogen ground-state energy is therefore the sixth.

JEE Main · 2021 · 17 Mar 2021 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Modern Physics →

More JEE Main questions on Modern Physics

7.9 MeV α-particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) ______ m.
[ $\frac{1}{4 π ϵ _{0}} = 9 \times 1 0^{9}$ Nm²/C² and electron charge $= 1.6 \times 1 0^{- 19}$ C]
JEE Main 2026View solution →
The minimum frequency of photon required to break a particle of mass 15.348 amu into $4 α$ particles is ______ kHz.
[mass of He nucleus = 4.002 amu, $1$ amu $= 1.66 \times 1 0^{- 27}$ kg, $h = 6.6 \times 1 0^{- 34}$ J.s and $c = 3 \times 1 0^{8}$ m/s]
JEE Main 2026View solution →
The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly $____$ nm.
JEE Main 2026View solution →
Light is incident on a metallic plate having work function $110 \times 1 0^{- 20} J$ . If the produced photoelectrons have zero kinetic energy then the angular frequency of the incident light is ______ $rad / s$ . ( …
JEE Main 2026View solution →
The energy of an electron in an orbit of the Bohr's atom is $- 0.04 E_{0} eV$ where $E_{0}$ is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then …
JEE Main 2026View solution →
A particle having electric charge $3 \times 1 0^{- 19} C$ and mass $6 \times 1 0^{- 27} kg$ is accelerated by applying an electric potential of 1.21 V . Wavelength of the matter wave associated with the particle is $α \times 1 0^{- 12} m$ . The va …
JEE Main 2026View solution →