19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
In the Rutherford scattering experiment, most α-particles passed straight through the gold foil because
The smallest and lightest positive ion obtained from hydrogen is called
The electrical discharge through gases could be observed only at
Positive rays (canal rays) are:
Mass of neutron is about ________ times the mass of the electron.
The e/m ratio for anode rays (positive rays) in comparison to cathode rays is:
Atoms can be further divided into sub-particles like
Early Indian and Greek philosophers were of the view that 'A' are the fundamental building blocks of matter. Here, 'A' refers to
The correct order of increasing energy of orbitals in hydrogen atom is
[CBSE AIPMT 2015] The number of d-electrons in Fe²⁺ (Z = 26) is NOT equal to the number of electrons in which one of the following?
[NEET 2019] Orbital having 3 angular nodes and 3 total nodes is
[NEET 2019] 4d, 5p, 5f and 6p orbitals are arranged in order of decreasing energy. The correct option 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)
[NEET 2021] From the following pairs, which one is NOT an isoelectronic pair?
The oil drop experiment was developed by
[Haryana PMT 2009] The number of radial nodes of 3s and 2p-orbitals are respectively
The relationship between frequency (ν), wavelength (λ) and velocity of light (c) is
The number of wavelengths per unit length is called
Calculate the frequency of yellow radiation having wavelength 5800 Å.
Rank the following radiations from highest energy to lowest: X-ray, ultraviolet, visible, infrared, microwave
The relation between energy of radiation and its frequency was given by:
[NEET 2016] How many electrons can fit in the orbital for which n = 3 and l = 1?
Which is NOT a characteristic of Planck's quantum theory of radiation?
According to Planck, the smallest quantity of energy that can be emitted or absorbed in the form of electromagnetic radiation is called
The number of photons of light with wave number ν̄ = 2.5 × 10⁶ m⁻¹ necessary to provide 1 J of energy are