Synthetic detergents have advantage over soaps because: MCQ with Answer and Explanation

Explanation:
CaSO₄·½H₂O readily absorbs moisture to set to CaSO₄·2H₂O (gypsum), becoming hard and useless for molding. So it must be kept dry. Reaction: CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O.

Explanation:
Burning of magnesium ribbon produces a new substance, magnesium oxide (MgO), and releases heat and light, which are indicators of a chemical change. Melting, dissolving, and boiling are physical changes because the chemical composition remains unchanged. Chemical changes are generally irreversible.

Explanation:
J.J. Thomson discovered the electron and proposed the 'plum pudding' model (positive sphere with embedded electrons). Rutherford proposed the nuclear model after the gold foil experiment. Bohr gave quantized orbits. Dalton gave the solid sphere model.