Dalton's atomic theory successfully explained :
(i) Law of conservation of mass
(ii) Law of constant proportion
(iii) Law of radioactivity
(iv) Law of multiple proportion
Correct option is :

Question

Accepted Answer

Dalton's atomic theory is a fundamental scientific theory that laid the groundwork for our understanding of atomic structure and chemical reactions. It successfully explained several key laws of chemistry, which are reflected in Option 3: (i) Law of conservation of mass, (ii) Law of constant proportion, and (iv) Law of multiple proportion. Here is a detailed explanation of why Option 3 is correct:

1. **Law of Conservation of Mass**: Dalton's atomic theory posits that atoms are indivisible particles that cannot be created or destroyed in a chemical reaction. This directly supports the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products, as the atoms are simply rearranged.

2. **Law of Constant Proportion**: According to Dalton's theory, a chemical compound is composed of a fixed ratio of atoms, each with a specific mass. This explains the Law of Constant Proportion, which states that a given chemical compound always contains its component elements in a fixed ratio by mass. For example, water (H₂O) always consists of hydrogen and oxygen in a 2:1 ratio by atom count, which translates to a fixed mass ratio.

3. **Law of Multiple Proportion**: Dalton's theory also accounts for the Law of Multiple Proportion, which states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in the ratio of small whole numbers. This is explained by the idea that atoms combine in simple whole-number ratios.

Now, let's explain why the other options are incorrect:

- **Option 1 (i), (iii), and (iv)**: This option incorrectly includes the Law of Radioactivity (iii), which was not explained by Dalton's atomic theory. Radioactivity involves the decay of unstable atomic nuclei, a concept that was discovered later and is not addressed by Dalton's theory.

- **Option 2 (ii), (iii), and (iv)**: Similar to Option 1, this option incorrectly includes the Law of Radioactivity (iii). Additionally, it omits the Law of Conservation of Mass (i), which is a fundamental aspect explained by Dalton's theory.

- **Option 4 (i), (ii), and (iii)**: This option also incorrectly includes the Law of Radioactivity (iii) and omits the Law of Multiple Proportion (iv), which is a key aspect explained by Dalton's atomic theory.

In conclusion, Option 3 is the correct answer because Dalton's atomic theory successfully explains the Law of Conservation of Mass, the Law of Constant Proportion, and the Law of Multiple Proportion.