Question

the electron configuration of element y ends in $s^2p^4$. what is the symbol for the ion most commonly formed by this element?
a $y^{2+}$
b $y^-$
c $y^{6+}$
d $y^{2-}$

Explanation:

Step1: Analyze valence electrons

Element Y has valence configuration $s^2p^4$, so it has $2+4=6$ valence electrons.

Step2: Determine stable ion state

Atoms gain/lose electrons to reach 8 valence electrons (octet rule). Y needs 2 more electrons to fill its valence shell.

Step3: Identify the ion symbol

Gaining 2 electrons gives a 2- charge: $Y^{2-}$.

Answer:

d. $Y^{2-}$