Question

Which among the following is a heaviest isotope of water?

• A. $\mathrm{T_2^{17}O}$
• B. $\mathrm{T_2^{16}O}$
• C. $\mathrm{HD^{18}O}$
• D. $\mathrm{T_2^{18}O}$

Hint:

Heaviest isotope is identified by the highest total mass number of all atoms present in the molecule.

Answer 1

The Correct Option is D

Step 1: Understanding isotopes of water.
Isotopes of water differ in the isotopic composition of hydrogen (H, D, T) and oxygen ($^{16}$O, $^{17}$O, $^{18}$O). Heavier isotopes contain nuclei with greater mass numbers.

Step 2: Comparison of given options.
Tritium (T) is the heaviest isotope of hydrogen, and $^{18}$O is the heaviest naturally occurring isotope of oxygen among the given options.

Step 3: Identifying the heaviest combination.
A molecule containing two tritium atoms and one $^{18}$O atom will have the highest molecular mass.

Step 4: Conclusion.
Therefore, the heaviest isotope of water is (D) $\mathrm{T_2^{18O}$}.