Which of the following isotope symbols can't be correct? (a) (b) (c) (d)

Isotope notation is a way to represent isotopes of an element, typically written as 'A/Z Element', where 'A' is the mass number (total protons and neutrons) and 'Z' is the atomic number (number of protons). Understanding this notation is crucial for identifying whether a given isotope symbol is valid based on the number of protons and neutrons.

The atomic number (Z) defines the identity of an element and corresponds to the number of protons in its nucleus, while the mass number (A) is the sum of protons and neutrons. A valid isotope symbol must have a mass number greater than or equal to the atomic number, as it cannot have a negative number of neutrons.

Isotopes can be stable or unstable, with unstable isotopes undergoing radioactive decay. Understanding the stability of isotopes is important when evaluating the correctness of isotope symbols, as certain combinations of protons and neutrons may not exist in nature or may be highly unstable, leading to invalid representations.