Question

Which of the following pairs are isotopes? Give reasons for your choice:

(i) ${}_{26}^{58}A$, ${}_{28}^{58}B$ or (ii) ${}_{35}^{79}X$, ${}_{35}^{80}Y$

Answer 1

so option (ii) ${}_{35}^{79}X$, ${}_{35}^{80}Y$

ISOTOPES:- Isotopes are the atoms of the element having the same atomic number (Z) but different atomic mass (A). This means isotopes of an element have the same number of protons but the different number of the neutron in their nuclei.

For Eg. Carbon has two Isotopes-

1) C-12 - Atomic no. (Z) =6 and mass no. (A) = 12
and thus has 6 Neutrons

2) C-14 - Atomic no. (Z) = 6 and Mass no. (A) = 14
and thus has 8 Neutrons.