Question

An element M has the atomic number 9 and atomic mass 17. Its ion will be represented by:

• A. $M$
• B. $M^{2+}$
• C. $M^{-}$
• D. $M^{2-}$

Answer 1

Answer: (C)

$M^{-}$

The atomic number of element M $=9$.
The electronic configuration of element M $=2,7$.
Element M need only one electron to complete the octet as 2,8.
Element M will have one minus charge due to one added electron in the valence shell $=M^{-}$.