Question

Dalton's theory of same element have same mass and properties was proved wrong with the invention of:

• A. molecules
• B. isotopes
• C. neutrons
• D. compounds

Answer 1

The correct option is B isotopes

According to Dalton's atomic theory, atoms of an element are identical in mass, size and many other chemicals or physical properties.

But, practically we observe that atoms of several elements differ in their densities and masses.

These atoms with the different masses are known as isotopes. For example, Chlorine (Cl) has 2 isotopes with the mass numbers of 35 and 37.

Hence, correct option is $\text{B}$.