Question

From the following nuclei, select the pairs of isotopes.
$\left(i{)}_{92}^{238}U\right(ii{)}_{90}^{234}Th\left(iii{)}_{92}^{234}U\right(iv{)}_{91}^{234}Pa$

• A. (i) and (iii) are isotopes
• B. (i) and (iv) are isotopes
• C. (i) and (ii) are isotopes
• D. (ii) and (iii) are isotopes

Answer 1

The correct option is A (i) and (iii) are isotopes

Isotopes are species that have the same atomic number but different mass numbers. (i) and (iii) are isotopes since they have the same atomic number.