Question

A highway engineer is researching de-icing compounds for clearing ice from streets in winter. She wants a compound that has +2 ions and -1 ions in it. Which would work?
1- aluminum combined with sulfur
2- potassium combined with iodine
3- magnesium combined with chlorine
4- silicon combined with oxygen ​

Answer 1

Magnesium combined with chlorine.

How?

• Look at the question .Compound has -1 charge in it .Hence it contains Halogen.
• Looking at the options Option B and C contain Iodine and chlorine i.e halogens .

Now come to metals side.

• Potassium has valency 1(Look the Electronic configuration below)

$\\ \sf\longmapsto 1s^22s^22p^63s^23p^64s^1$

Hence it will contain +1 charge which is omitted directly .

Now come to option C.

• Magnesium has charge +2(Look at EC below

$\\ \sf\longmapsto 1s^22s^22p^63s^2$

Hence the compound formed is given by

$\\ \sf\longmapsto MgCl_2$

Hence option C is correct.