Which scientist proposed the law of conservation of mass?
A. John Dalton
B. Ernest Rutherford
C. Antoine Lavoisier
D. J. J. Thomson
Answer: Option C
Solution (By JKExamLibrary)
Antoine Lavoisier is known as the father of modern chemistry and formulated the law of conservation of mass—mass is neither created nor destroyed in a chemical reaction. Dalton's atomic theory supported this law. Thomson discovered electron. Rutherford discovered nucleus. Lavoisier also named oxygen and hydrogen and established the role of oxygen in combustion.
Explanation:
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:
Diamond is a giant covalent structure where each carbon is tetrahedrally bonded to four others via strong covalent bonds. Melting requires breaking numerous strong bonds, needing very high temperature (~3500°C). Graphite also has high melting point. Molecular solids like ice have low melting points. Carbon alone doesn't guarantee high m.p.; it's the structure.
Explanation:
Cation exchange resins contain Na⁺ ions which are replaced by Ca²⁺/Mg²⁺, softening the water. Anion exchange can also be used for deionization. Washing soda precipitates Ca/Mg.
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