Beryllium, be, and chlorine, ci, form a binary ionic compund with a one-to-two ration of beryllium ions to chloride ions. the formula for the compund is
a)be2cl
b)becl
c)becl2
d)be2cl2

The correct answer is option C.

Explanation:

Binary compounds are compounds which are made up of only two types of different elements ,forexample : HCl, NaCl etc

Beryllium, Be, and chlorine, Ci, form a binary ionic compound:

Ratio of beryllium to chlorine atom = 1 : 2

If there are x atoms of beryllium, then there 2 x atoms of chlorine atoms in the ionic compound:

The formula for the compound is  

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be