Question

consider a neutral atom with 30 protons and 34 neutrons. the mass number for this atom is
30.
32.
34.
64.
94.
question 2 (1 point)
given the following: $_{19}^{41}x$, $_{19}^{39}x$, $_{20}^{41}x$, and $_{18}^{39}x$. which are isotopes of each other?
$_{19}^{41}x$ and $_{19}^{39}x$ are isotopes of each other.
$_{19}^{41}x$ and $_{20}^{41}x$ are isotopes of each other; and $_{19}^{39}x$ and $_{18}^{39}x$ are isotopes of each other.
$_{19}^{41}x$, $_{19}^{39}x$, $_{20}^{41}x$, and $_{18}^{39}x$ are isotopes of each other.
none are isotopes of each other.

Explanation:

Step1: Recall mass - number formula

The mass number ($A$) of an atom is the sum of the number of protons ($p$) and neutrons ($n$), i.e., $A=p + n$.

Step2: Calculate mass number

Given $p = 30$ and $n = 34$, then $A=30 + 34=64$.

Step3: Recall isotope definition

Isotopes are atoms of the same element (same atomic number, $Z$) with different mass numbers. The atomic number is the sub - script in the notation $^{A}_{Z}X$.

Step4: Identify isotopes

For $^{41}_{19}X$ and $^{39}_{19}X$, the atomic number ($Z = 19$) is the same, so they are isotopes of each other. For $^{41}_{20}X$ and $^{39}_{18}X$, the atomic numbers are different ($Z = 20$ and $Z = 18$ respectively), so they are not isotopes of the others.

Answer:

Question 1: 64.
Question 2: $^{41}_{19}X$ and $^{39}_{19}X$ are isotopes of each other.