Question

$M^{2+}$ ion is isoelectronic of $S{O}_2$ and has $(Z+2)$ neutrons ($Z$ is atomic number of $M$). Thus, ionic mass of $M^{2+}$ is :

• A. $70$
• B. $66$
• C. $68$
• D. $64$

Answer 1

The correct option is A $70$

$M^{2+}$ ion is isoelectronic of $S{O}_2$.

Number of electrons and number of protons in M $=32+2=34=Z$.

Number of neutrons $=34+2=36$.

So, molar mass $=34+36=70$ g/mol $=$ ionic molar mass.