Answer:
Step-by-step explanation:
The reaction expression is given as:
⁴⁰₁₈ Ar → X + ⁰₁B
To solve this problem, we must bear in mind that both mass number and atomic number must be conserved.
So;
For the mass number:
40 = A + 0
A = 40
For atomic number:
18 = Z + 1
Z = 18 - 1 = 17
An atom is identifiable by the atomic number. Since the atomic number of X is 17 then it is Cl, chlorine