Answer:
The answer to your question is: Letter A is the correct one
Explanation:
₄₅Ca = protons = 20; neutrons = 25; electrons = 20
in the isotope Calcium-45, contains 20 protons, 20 electrons, and 25 neutrons are present.
Isotope:
it is an alternate form of an element (atom) that have same number of proton but different number of neutron.
Or an isotope have same atomic number but different atomic mass.
For Example-
₄₅Ca (Calcium-45) is an isotope of calcium.
Atomic number or number of proton = 20
Number of neutrons - 25
Atomic mass = 45
Therefore, in the isotope Calcium-45, contains 20 protons, 20 electrons, and 25 neutrons are present.
To know more about Isotope,
https://brainly.com/question/13214440
