Chemistry Question Bank

The frequency of light emitted for the transition n = 4 to n = 2 of He⁺ is equal to the transition in H atom corresponding to which of the following?

PASSAGE: In a mixture of H–He⁺ gas (He⁺ is singly ionised He atom), H atoms and He⁺ ions are excited to their respective first excited states. Subsequently, H atoms transfer their total excitation energy to He⁺ ions (…

[Manipal 2008] The radius of the nucleus of mass number A is given by r = 1.25 × 10⁻¹³ × A^(1/3) cm. The radius of the atom is 1.0 Å. For mass number A = 64, the fraction of atomic volume occupied by the nucleus is

[Kerala CEE 2014] The ratio of de Broglie wavelengths of a deuterium atom to that of an α-particle, when the velocity of deuterium is five times that of the α-particle, is

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

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

[NEET 2019] In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is (Bohr radius a₀ = 52.9 pm)

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

If the total energy of an electron in the 1st shell of H atom = 0.0 eV (reference shifted), then its potential energy in the 1st excited state would be

The ionization enthalpy of hydrogen atom is 1.312 × 10⁶ J mol⁻¹. The energy required to excite the electron from n = 1 to n = 2 is