19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
[Haryana PMT 2010] The electronic configuration 1s², 2s², 2p¹ₓ 2p¹ᵧ 2p¹_z for nitrogen (not 1s², 2s², 2p²ₓ 2p¹ᵧ 2p⁰_z) is determined by
[VMMC 2010] Which of the following pairs is isoelectronic?
[CBSE AIPMT 2011] The total number of atomic orbitals in the fourth energy level of an atom is
[KCET 2012] The nitride ion in lithium nitride (Li₃N) is composed of
[AIPMT 2012] Maximum number of electrons in a subshell with l = 3 and n = 4 is
The oil drop experiment was developed by
Early Indian and Greek philosophers were of the view that 'A' are the fundamental building blocks of matter. Here, 'A' refers to
Mass of neutron is about ________ times the mass of the electron.
Positive rays (canal rays) are:
The relationship between frequency (ν), wavelength (λ) and velocity of light (c) is
The number of wavelengths per unit length is called
The relation between energy of radiation and its frequency was given by:
According to Planck, the smallest quantity of energy that can be emitted or absorbed in the form of electromagnetic radiation is called
Increasing the frequency of incident radiation in the photoelectric effect increases the:
The photoelectric effect shows:
The minimum frequency ν₀, below which the photoelectric effect is not observed, is called
The energy of an electron in the 3rd orbit of hydrogen atom is
Electronic energy is negative because
The value of a₀ (Bohr radius) in the expression for the radius of nth orbit of hydrogen atom (rₙ = n²a₀) is
In the hydrogen spectrum, the Balmer series lies in which region?
Which series in the hydrogen spectrum lies in the ultraviolet region?
Assertion (A): Atoms are electrically neutral. Reason (R): Number of protons and electrons are different in an atom.
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.
[Manipal 2008] Deflection of a few α-particles back on hitting a thin gold foil shows that
[NEET 2016] Two electrons occupying the same orbital are distinguished by