Question

The mass number of an isotope of uranium is 238, and its atomic number is 92. Which symbol best represents this isotope of uranium?
Subscript 92 upper U.
Superscript 238 subscript 92 upper U.
Superscript 92 subscript 238 upper U.
Superscript 92 upper U.

Answer 1

The correct symbol is: superscript 238, subscript 92, U — written as ²³⁸₉₂U.

Reason: the mass number (A = 238) is written as a superscript left of the element symbol and the atomic number (Z = 92) as a subscript left of the symbol. (Neutrons = 238 − 92 = 146.)