Question

The following properties belong to .........
a. The number of nucleons in the atoms of different elements remains the same
b. The atomic number for different elements is different
c. The number of protons and electrons is always equal

• A. Isotopes
• B. Isobars
• C. Isotones
• D. None of the above

Answer 1

Answer: (B)

Isobars

Atoms of different elements which have the same mass number, A (number of neutrons and protons in the nuclei) but different atomic number, Z (number of protons or electrons) are called isobars. For example, $18A{r}^{40}$ & ${}_{20}C{a}^{40}$ have same mass number of $40$ but different atomic numbers $18$ and $20$ respectively.