the symbol for a radioactive nuclide is $_{90}^{234}th$. which statement is correct?\nthe atomic number of…

Explanation:

Step1: Recall nuclide notation

In the notation ${Z}^{A}X$, $A$ is the mass - number and $Z$ is the atomic number. For ${90}^{234}Th$, $A = 234$ and $Z=90$.

Step2: Recall definitions of mass - number and atomic number

The atomic number $Z$ is the number of protons in the nucleus. The mass number $A$ is the sum of protons and neutrons in the nucleus. Neutrons $N=A - Z$.

Step3: Analyze each option

• Option 1: The atomic number of $_{90}^{234}Th$ is 90. This is correct as the sub - script in the nuclide notation represents the atomic number.
• Option 2: The mass number $A = 234$, not 144.
• Option 3: Neutrons $N=A - Z=234 - 90 = 144$, not 324.
• Option 4: The number of protons is equal to the atomic number $Z = 90$, not 234.

Answer:

The atomic number of the radioactive nuclide is 90.