WAEC - Chemistry (2003 - No. 3)
An element X with electronic configuration \(1S^22S^22P^63S^2\) combines with another element Y with the configuration \(1S^2S^22P^23S^23P^5\). What is the formula of the compound formed?
X2Y5
X2Y3
XY3
XY2
Vysvetlenie
Element X has a valency of 2 while Y has a valency of 1,
so they exchange valency to form \( XY_2\)