A free original English–Hindi lesson on atoms, molecules, ions and chemical formulae. Read symbols and grouped formulae without confusing subscripts, coefficients or charges. Use supplied ionic charges to find the smallest neutral ratio, preserve polyatomic groups, and distinguish molecular mass from formula-unit mass using given atomic masses. Four worked cases, original representations, an analogy, a quick reference and five explained questions connect notation to particle meaning. Ionic crystals are not described as collections of isolated molecules, and given molecular formulae are not reduced as if they were ionic ratios. This focused foundation supports later atomic structure and equation balancing; it does not claim complete RRB chemistry coverage.