Detailed Explanation:

Dalton's atomic theory (1808) explained three fundamental laws of chemical combination:

✅ Law of conservation of mass: Atoms are neither created nor destroyed in reactions, so total mass remains constant.

✅ Law of constant composition: A compound always contains the same elements in fixed proportions by mass.

✅ Law of multiple proportions: When two elements form multiple compounds, mass ratios are simple whole numbers.

❌ Law of radioactivity: Radioactivity (discovered by Becquerel, 1896) involves nuclear changes, not explained by Dalton's indivisible atom concept.