Chemistry Question Bank

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

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

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

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

The emission spectra of He⁺ ions show 6 different photons. What will be the minimum wavelength during the transition? (R_H = Rydberg constant)

A mixture of ethane and ethene occupies 40 litre at 1.00 atm and at 400 K. The mixture reacts completely with 130 g of to produce and . Assuming ideal gas behavior, calculate the mole fraction of and in the mixture.

What volume of 0.010 M is required to react completely with 30 g of an aqueous acetic acid solution in which mole fraction of acetic acid is 0.15?

The molecular mass of an organic acid was determined by the study of its barium salt. 4.290 g of salt was quantitatively converted to free acid by the reaction with 21.64 mL of . The barium salt was found to have two …

A 2.00 g portion of a sample containing NaBr and was dissolved and diluted to 250 mL. One fifth aliquot portions were titrated by silver nitrate, an average of 42.5 mL solution being required for the aliquot portion. …

An element (X) reacts with hydrogen leading to formation of a class of compounds that is analogous to hydrocarbons. 5.00 g of X forms 5.625 g of a mixture of two compounds of in the molar ratio of 2:1. Determine the m…

6.0 g of a sample containing and is dissolved in 100 mL water. A 10 mL portion of this solution on treatment with solution results in complete precipitation of and giving 0.9065 gram of precipitate. The precipitate th…