Chemistry Question Bank

[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

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 (…

Assertion (A): It is impossible to determine the exact position and exact momentum of an electron simultaneously. Reason (R): The path of an electron in an atom is clearly defined.

Assertion (A): For Balmer series of hydrogen spectrum, the value of n₁ = 2 and n₂ = 3, 4, 5 ... Reason (R): The value of n for a line in Balmer series having the highest wavelength is n₁=4 and n₂=6.

Assertion (A): The radius of the first orbit of hydrogen atom is 0.529 Å. Reason (R): Radius of each circular orbit rₙ = 0.529 × (n²/Z) Å, where n = 1,2,3 and Z = atomic number.

Assertion (A): Atoms are electrically neutral. Reason (R): Number of protons and electrons are different in an atom.

The number of unpaired d-electrons retained in Fe²⁺ ion (At. no. of Fe = 26) is

The correct set of four quantum numbers for the valence electron of rubidium (Z = 37) is

In any subshell, the maximum number of electrons having the same value of spin quantum number is

A stream of electrons is passed between two charged plates at potential difference V (esu). If e and m are charge and mass of electron, the value of h/λ (λ = de Broglie wavelength) is

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?

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

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

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

[Haryana PMT 2009] The number of nodal planes in the pₓ orbital is

[AMU 2009] The radius of the Bohr orbit of the H-atom is r. Then the radius of the first orbit of Li²⁺ will be

[Manipal 2009] For f-orbital, the values of magnetic quantum number m are

[Manipal 2009] The uncertainty in position of an electron (m = 9.1 × 10⁻²⁸ g) moving with velocity 3.0 × 10⁴ cm s⁻¹ accurate to 0.011% will be (h = 6.626 × 10⁻²⁷ erg·s)

[CBSE AIPMT 2009] Which of the following is NOT a permissible arrangement of electrons in an atom?

[Haryana PMT 2010] The electronic configuration 1s², 2s², 2p¹ₓ 2p¹ᵧ 2p¹_z for nitrogen (not 1s², 2s², 2p²ₓ 2p¹ᵧ 2p⁰_z) is determined by

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

The velocity of an electron in the second shell of hydrogen atom is

Bohr's theory is NOT applicable to:

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