the mass number of an isotope of uranium is 238, and its atomic number is 92. which symbol best represents…

Explanation:

Step1: Recall isotope notation

The notation for an isotope is $_{Z}^{A}X$, where $A$ is the mass - number, $Z$ is the atomic number and $X$ is the chemical symbol.

Step2: Identify values for uranium

For uranium, the atomic number $Z = 92$ and the mass number $A=238$, and the chemical symbol is $U$.

Step3: Write the correct symbol

The correct symbol for this uranium isotope is $_{92}^{238}U$.

Answer:

$_{92}^{238}U$ (corresponding to the second option in the multiple - choice list)