1)
- Atomic number (B) = 8
- Number of protons (A) = 8
- Symbol of element - O
2)
Mass number and atomic number
The total number of protons and neutrons in an atom's nucleus is its mass number.
The quantity of protons in an atom's nucleus is known as its atomic number. It is an essential characteristic that gives an element its own identity.
Atomic number = Mass number - Number of neutrons
= 15 - 7 = 8
Atomic number (B) = 8
Number of protons (A) = 8
Symbol of element - O
2)
Atomic number = Mass number - Number of neutrons
Number of neutrons = Mass number - Atomic number
= 56 - 26
= 30
Hence;
D = 26
E = 30
F = Zn