19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Which of the following electronic transitions in a hydrogen atom will require the largest amount of energy?
The most probable radius (in pm) for finding the electron in He⁺ is
[NEET 2022] If the radius of the second Bohr orbit of He⁺ ion is 105.8 pm, what is the radius of the third Bohr orbit of Li²⁺ ion?
Let mₚ be the mass of a proton, mₙ that of a neutron, M₁ that of a ²⁰₁₀Ne nucleus and M₂ that of a ⁴⁰₂₀Ca nucleus. Then
How long would it take a radiowave of frequency 6 × 10³ s⁻¹ to travel from Mars to Earth, a distance of 8 × 10⁷ km?
Suppose 10⁻¹⁷ J of light energy is needed by the interior of the human eye to see an object. The number of photons of green light (λ = 550 nm) needed to see the object are
A 4000 Å photon is used to break the I₂ molecule. The bond dissociation energy of I₂ is 246.5 kJ/mol. The % of photon energy converted to kinetic energy of iodine atoms is
A photon of 300 nm is absorbed by a gas and then re-emits two photons. One re-emitted photon has wavelength 496 nm. The wavelength of the second re-emitted photon is
A 20 W light source emits monochromatic light of wavelength 600 nm. The number of photons ejected per second expressed in terms of Avogadro's constant N_Av is approximately
If a certain metal is irradiated with two different light radiations of frequency x and 2x, the maximum kinetic energies of ejected electrons are y and 3y respectively. The threshold frequency of the metal will be
The Bohr orbit radius for hydrogen atom (n = 1) is 0.529 Å. The radius for the first excited state (n = 2) orbit is
Ultraviolet light of 6.2 eV falls on an aluminium surface (work function = 4.2 eV). The kinetic energy (in joule) of the fastest electron emitted is approximately:
Energy of electron of hydrogen atom in the second Bohr orbit is
The threshold wavelength for the photoelectric effect on sodium is 5000 Å. Its work function is:
If the threshold frequency of a metal for the photoelectric effect is ν₀, which of the following will NOT happen?
The energy of an electron in the 3rd orbit of hydrogen atom is
[NEET 2021] A radio station broadcasts at frequency 1368 kHz. The wavelength of electromagnetic radiation emitted is (c = 3 × 10⁸ m/s)
As an electron moves away from the nucleus, its potential energy
When sodium compounds are heated in a Bunsen burner flame, they emit light at 5890 Å. If 1.0 × 10⁻⁴ moles of sodium atoms each emit one photon of this wavelength, how much energy (in kJ) is emitted?
Find the frequency of light that corresponds to photons of energy 5.0 × 10⁻⁵ erg
The emission spectra of He⁺ ions show 6 different photons (from transitions to ground state). The quantum number n of the state finally populated in He⁺ ions from the H–He⁺ mixture experiment (after H transfers excita…
In the H–He⁺ mixture experiment, the wavelength of light emitted in the visible region by He⁺ ions after collisions with H atoms is
In the H–He⁺ mixture experiment, the ratio of potential energy of the n=2 electron for the H atom to that of He⁺ ion is
The correct ground state electronic configuration of chromium atom (Z = 24) is
Pauli's exclusion principle states that