Question

Amongst the following statements, that which was not proposed by Dalton was:
A. chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
B. when gases combine or reproduce in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same T and P.
C. All the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.
D. matter consists of indivisible atoms.

Answer 1

Hint: The atomic concept of matter was put forth by John Dalton (1808) to explain the laws of chemical reaction. He considered atoms as structureless indivisible indestructible particles. Studying the postulates of Dalton’s atomic theory, we can answer the question.

Complete Solution :
In 1801, John Dalton proposed the atomic theory according to which:
a. All matter is composed of atoms, tiny, indivisible and indestructible.
b. chemical reactions result in the combination, separation or rearrangement of atoms. In other words atoms are neither created nor destroyed in a chemical reaction.
c. Atoms of a particular atom are identical in mass, size and other properties. Atoms of different elements differ in mass.
- It was Gay-Lussac who proposed “the law of combining volumes”, according to which:
When gases combine or reproduce in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same temperature T and pressure P.
So, the correct answer is “Option B”.

Note: Dalton’s atomic theory is based on law of multiple proportions and the law of constant proportions. In addition, Dalton’s theory is in accordance with the law of conservation of mass.
- However, Dalton’s idea of the atom being indivisible was disapproved later by the discovery of radioactivity. According to the Modern atomic theory, atoms are composed of three fundamental particles, namely protons, neutrons and electrons.