Question

The first atomic theory of matter was proposed by:-
(A) Rutherford
(B) John Dalton
(C) Niels Bohr
(D) James adwickch

Answer 1

Atomic theory is a scientific theory of the nature of matter, which states that matter is composed of discrete units called atoms. Atomic theory of matter was first proposed by John Dalton. Dalton's atomic theory was the first complete attempt to describe all the matter in the terms of atoms and their properties.

Complete step by step answer:
-Many of the scientists gave the concept for the atomic theory of the matter. But, the first atomic theory of matter was proposed by John Dalton. John Dalton (1766-1844) developed the first useful atomic theory of matter.
-For the research he did into colour blindness, led him to be also referred to as Daltonism in his honour.
Postulates of Dalton's atomic theory are as follows:-
-All matter is made up of tiny, indivisible particles called atoms.
-All atoms of a specific element are identical in mass, size, and other properties. However, atoms of different elements exhibit different properties and vary in mass and size.
-Atoms can neither be created nor destroyed. Furthermore, atoms cannot be divided into smaller particles.
-Atoms of different elements can combine with each other in fixed whole-number ratios in order to form compounds.
-Atoms can be rearranged, combined, or separated in chemical reactions.

Hence option B is correct.

Note:
Dalton based his theory on the law of conservation of mass and the law of constant composition. Though, Dalton was first to discover the atomic theory of matter but there was certain limitations or drawbacks of his atomic theory which are as follows:-
Limitations of Dalton's Atomic Theory:
A) Atoms consist of particles like electrons, protons, and neutrons but Dalton said atoms are indivisible and they can neither be created nor be destroyed.
B)Discovery of isotopes revealed that the atoms of the same element possess different weights.