JEE Main 2024 · 4 April · evening · Single correct · +4 / −1
Choose the Incorrect Statement about Dalton's Atomic Theory
- (a) Compounds are formed when atoms of different elements combine in any ratio.
- (b) Matter consists of indivisible atoms.
- (c) chemical reactions involve reorganization of atoms
- (d) All the atoms of a given element have identical properties including identical mass.
Answer and solution
Answer (a) Compounds are formed when atoms of different elements combine in any ratio.
Solution
Chemistry ma’am · 3 steps
Match each line to what Dalton actually said; the slip is the word 'any' where he said 'fixed ratio'.
- What is asked. Judge each statement against Dalton's own postulates, not against modern atomic theory. A postulate that was later proved wrong is still a correct statement of Dalton's theory.
Option Dalton's postulate Statement matches? (a) Atoms of different elements combine in a fixed, simple whole-number ratio No, it says any ratio (b) Matter is made of indivisible atoms Yes (c) A chemical reaction only rearranges atoms; none are created or destroyed Yes (d) All atoms of one element are identical, including in mass Yes - Why fixed matters. The fixed ratio is how Dalton explained the law of definite proportions. Water is always H₂O, never hydrogen and oxygen joined in some random ratio.
- So. Only (a) misstates the theory, so (a) is the incorrect statement.
The idea to keep. In 'Dalton's theory' questions, check the wording against his postulates, not against what we know today. Watch for words like 'any' replacing 'fixed' or 'simple whole-number'.
Answer from the NTA final answer key. Solution by PrepWiser.