NCERT Exemplar Solutions Class 9 Science Solutions for Structure of the Atom - Exercise in Chapter 4 - Structure of the Atom

Question 8 Structure of the Atom - Exercise

Dalton’s atomic theory successfully explained

(i) Law of conservation of mass

(ii) Law of constant composition

(iii) Law of radioactivity

(iv) Law of multiple proportion

(a) (i), (ii) and (iii)

(b) (i), (iii) and (iv)

(c) (ii), (iii) and (iv)

(d) (i), (ii) and (iv)


Answer is (d) (i), (ii) and (iv)


Dalton’s theory explains the Law of conservation of mass, Law of constant composition, Law of multiple proportions. But it never gives any details of the Law of radioactivity.

A theory of chemical combination, first stated by John Dalton in 1803.

It involves the following postulates:

(1) Elements consist of indivisible small particles (atoms).

(2) All atoms of the same element are identical; different elements have different types of atom.

(3) Atoms can neither be created nor destroyed.

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