Hydrogen chloride is a polar covalent bond because the shared electron pair is unequally shared due to the higher electronegativity of chlorine (3.0) compared to hydrogen (2.1). The bond has a dipole moment, making HCl molecule polar. In water, HCl ionizes to H⁺ and Cl⁻, but the gaseous molecule is covalent. Pure ionic bonds exist in compounds like NaCl where electronegativity difference is large (>1.7).
Explanation:
Calcium (Ca²⁺) and magnesium (Mg²⁺) ions react with soap anions to form insoluble precipitates (scum), preventing lather. Sodium and potassium soaps are soluble and lather well. So detergents are preferred in hard water because their calcium/magnesium salts are soluble. Hardness is measured in terms of CaCO₃ equivalent.
Explanation:
Distilled water is considered the purest form of water because it is obtained by boiling water and condensing the steam, leaving almost all impurities, minerals, and salts behind. Rainwater is relatively pure but dissolves atmospheric gases and dust as it falls.
Explanation:
Thomson used cathode ray tubes to discover the electron and measure its charge-to-mass ratio (e/m). He proposed the 'plum pudding' model. Proton identified by Rutherford, neutron by Chadwick.
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