NEET 2020 Chemistry Question 124 Solution

For any nuclide represented as $$^{A}_{Z}\text{X}$$: - $$Z$$ is the atomic number (subscript), which represents the number of protons in the nucleus. - $$A$$ is the mass number (superscript), which represents the total number of nucleons (protons + neutrons).

For $$^{175}_{71}\text{Lu}$$: - Atomic number $$Z = 71$$. - Therefore, $$\text{Number of protons} = 71$$. - Because the atom is neutral (net charge = 0), the number of electrons equals the number of protons: $$\text{Number of electrons} = 71$$

$$\text{Number of neutrons} = A - Z = 175 - 71 = 104$$

The question explicitly demands: "protons, neutrons and electrons, respectively": $$\text{Protons} = 71, \quad \text{Neutrons} = 104, \quad \text{Electrons} = 71$$ This sequence corresponds exactly to Option (1).