Question

question 6
1 pts
a certain isotope x²⁺ contains 48 electrons and 75 neutrons. what is the mass number for this element?
50
121
123
125
46

Explanation:

Step1: Determine the number of protons

The ion $X^{2 +}$ has a charge of + 2, which means it has lost 2 electrons. If the ion has 48 electrons, then the neutral - atom of the element has $48 + 2=50$ electrons. In a neutral atom, the number of electrons is equal to the number of protons. So, the number of protons $p = 50$.

Step2: Calculate the mass number

The mass number $A$ of an atom is the sum of the number of protons and neutrons. Given that the number of neutrons $n = 75$ and the number of protons $p = 50$, then $A=p + n$. Substituting the values, we get $A=50+75 = 125$.

Answer:

125