Question

1. what is the isotope notation for a nucleus with 1 proton and 2 neutrons? a: mass #? x: symbol? z: atomic #?

Explanation:

Step1: Determine the atomic number (Z)

The number of protons is the atomic number. Since there is 1 proton, $Z = 1$.

Step2: Determine the mass number (A)

The mass number is the sum of protons and neutrons. With 1 proton and 2 neutrons, $A=1 + 2=3$.

Step3: Identify the element symbol (X)

The element with atomic number 1 is hydrogen, symbol H.

Step4: Write the isotope notation

The isotope notation is $_{Z}^{A}X$, so it is $_{1}^{3}H$.

Answer:

$_{1}^{3}H$