Periodic Classification and Elements

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers (n, l, m, s). This fundamental principle explains electron configuration in atoms and the structure of the periodic table. Option D contains a typo ('Pauti' instead of 'Pauli') but is clearly intended to be the correct answer.

Atoms consist of a central nucleus containing protons and neutrons, surrounded by electrons in orbitals. The nucleus contains nearly all the mass, while electrons occupy most of the volume. Atoms are not composed of electrons or protons alone - both components are essential for atomic structure.

Diamond is pure crystalline carbon (element C), making it an element. Ruby (Al2O3 with Cr), Sapphire (Al2O3 with Ti/Fe), and Emerald (Be3Al2Si6O18 with Cr) are all minerals containing multiple elements, not single elements.

The magnetic quantum number (m) describes the orientation of an orbital in space relative to an external magnetic field. Shape is described by azimuthal quantum number (l), size by principal quantum number (n), and spin is intrinsic.

Lead (Pb-208) is the most stable element because it has the highest binding energy per nucleon among all elements, and its particular isotope is doubly magic (82 protons, 126 neutrons). Uranium is radioactive and decays, hydrogen is reactive and forms compounds, and oxygen is highly reactive. Lead is the endpoint of many radioactive decay chains.

Electron configuration of Fe: [Ar] 3d⁶ 4s². If 2 electrons are removed then number of electrons left would be 6 and thus, there would be 4 unpaired electrons.

An atom is the smallest unit of an element that retains its chemical properties and can participate in chemical reactions. A molecule consists of two or more atoms bonded together. The nucleus is just the central part of an atom, while matter is a general term for anything that has mass and occupies space.

d-block elements are placed between s- and p-.

Correct option. The energy level of the highest occupied orbital in a metal at absolute zero is called as Fermi level.

Nitrogen has 5 electrons in the valency shell. To attain the configuration of noble gas, one nitrogen atom shares with three electrons with three electrons of the other nitrogen atom. Three paired of electrons constituent of triple bond.

‘n’ and ‘l’ can never have same numerical value, ‘l’ is always less than ‘n’, so it is not applicable for an electron in atom.

Element C (1s², 2s², 2p⁵) is one electron short of stable configuration. So, it readily shares one electron with its other atom. The mutual sharing of one pair of electrons between two atoms of C forms a diatomic molecule.

Valence electrons are the electrons in the outer-most shell of the atom.