Question 52: 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 \times 10^{-31} \mathrm{~kg}.
C. All the isotopes of a given element show 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 :
(1) A and E only
(2) B, C and E only
(3) A, B and C only
(4) C, D and E only
Answer: Option (2)
Explanation:
Statement A is incorrect because atoms are composed of three fundamental particles:
electrons, protons, and neutrons.
Statement B is correct as the mass of an electron is
9.10939 \times 10^{-31} \mathrm{~kg}.
Statement C is correct because isotopes of an element have the
same electronic configuration and therefore show identical chemical properties.
Statement D is incorrect because nucleons include protons and neutrons, not electrons.
Statement E is correct since Dalton’s atomic theory considered the atom
to be indivisible and the smallest unit of matter.
Hence, the correct statements are B, C and E, and the correct option is Option (2).