The chemical formula of nitric acid is: MCQ with Answer and Explanation

Explanation:
Chemical properties describe a substance's ability to undergo chemical changes—reactivity with acid, flammability, oxidation states, etc. Melting point, density, boiling point are physical properties that can be observed without changing composition. Reactivity with acid involves formation of new substances. A piece of magnesium reacting with HCl is a chemical change.

Explanation:
Elements in the same group (vertical column) have the same number of valence electrons, resulting in similar chemical properties. For example, all Group 1 elements have 1 valence electron (ns¹). The number of shells increases down the group. Atomic mass varies. This similarity was the basis for Mendeleev's grouping. Modern table uses atomic number for ordering.

Explanation:
Ostwald process: ammonia is oxidized with air over Pt-Rh catalyst to NO, then NO₂, then absorbed in water to give HNO₃. Haber for NH₃, Contact for H₂SO₄, Bayer for alumina from bauxite.