Answer:
This question is incomplete but the complete question is pasted below and the answer is 3
Question
Which element, represented by X, reacts with fluorine to produce the compound XF2?
(1) aluminum (3) magnesium
(2) argon (4) sodium
Explanation:
From the above question, X is unknown while F is fluorine.
For an unknown element to react with fluorine and the product will be XF2, the unknown element must have 2 electrons in its outermost shell and its ion must have a charge of 2+. Consider the equations below
X1+ + F1- ⇒ XF
X2+ + F1- ⇒XF2
X3+ + F1- ⇒XF3
From the options provided, aluminium ion has a charge of 3+, argon is a noble gas and hence has no charge, Magnesium has a charge of 2+ and sodium has a charge of 1+. Correspondingly, X is Magnesium and the compound formed will be MgF2.
NOTE:
Sodium will form NaF with flourine while aluminium will form AlF3 with fluorine. Argon will resist reaction with fluorine as it (argon) has achieved its octet configuration and hence stable.
