Let's complete the table as required.
### First Row:
- The number of protons is 20.
- The number of neutrons is also 20.
- The atomic number for an element is equal to the number of protons, so the atomic number (A) is 20.
- The mass number is the sum of the number of protons and neutrons, so the mass number (B) is 20 + 20 = 40.
- The element with atomic number 20 is Calcium, which has the symbol (C) 'Ca'.
### Second Row:
- The number of protons is 9.
- The mass number is given as 19.
- The atomic number (E) equals the number of protons, so E is 9.
- The number of neutrons (D) is calculated by subtracting the number of protons from the mass number: 19 - 9 = 10.
- The element with atomic number 9 is Fluorine, which has the symbol (F) 'F'.
Filling in the values, the completed table is:
[tex]\[
\begin{array}{|c|c|c|c|c|}
\hline
\begin{array}{c}
Number of \\
Protons
\end{array} & \begin{array}{c}
Number of \\
Neutrons
\end{array} & \begin{array}{c}
Atomic \\
Number
\end{array} & \begin{array}{c}
Mass \\
Number
\end{array} & \begin{array}{c}
Element \\
(symbol)
\end{array} \\
\hline 20 & 20 & 20 & 40 & Ca \\
\hline 9 & 10 & 9 & 19 & F \\
\hline
\end{array}
\][/tex]
And the specific answers to fill in are:
- A: 20
- B: 40
- C: Ca
- D: 10
- E: 9
