1.
An element, X, forms an ion with 10 electrons and forms the following types of compounds:
with group I metals or alkali metals: M 2 X and with group III metals M 2 X 3 . Element X is most
likely:
A. Cl
B.N
C. O
D. S
The answer is oxygen but i dont know why. Please explain why and why not the other elements.
Solution
Given: element forms ion with 10 electrons, verifying it for all
Cl -
=18 electrons
N 3-
=10 electrons
O 2-
=10 electrons
S 2-
=18 electrons
By this, oxygen and nitrogen can be the possibilities
Given: element forms M 2 X ( M=+1 and X=-2) with alkali metals and M 2 X 3 (M=+3 and X=-2)
with group 3 ,from this ion produced has -2 charge which is only oxygen. Hence, proved.