Select the correct statements from the following:

A. Atoms of all elements are composed of two fundamental pa

Question

Select the correct statements from the following:

A. Atoms of all elements are composed of two fundamental particles.
B. The mass of the electron is $9.10939 	imes 10^{-31}$ kg.
C. All the isotopes of a given element show the same chemical properties.
D. Protons and electrons are collectively known as nucleons.
E. Dalton's atomic theory regarded the atom as an ultimate particle of matter.

Choose the correct answer from the options given below:

Accepted Answer

1. **Statement A is False:** Atoms are generally composed of *three* fundamental particles: electrons, protons, and neutrons (except Hydrogen-1 which lacks neutrons).
2. **Statement B is True:** The standard rest mass of an electron is approximately $9.109 	imes 10^{-31} 	ext{ kg}$ [Class 11 Physics, Appendix A 3, Table].
3. **Statement C is True:** Isotopes of an element have the same number of electrons and protons (same electronic configuration), determining their chemical properties. They differ only in mass (neutrons).
4. **Statement D is False:** Nucleons are the particles residing in the nucleus, i.e., protons and *neutrons*. Electrons orbit the nucleus.
5. **Statement E is True:** Dalton's Atomic Theory originally proposed that the atom was indivisible and the ultimate particle of matter.

Therefore, the correct statements are B, C, and E.

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