a. 1:1

**Answer 1**

a. 1:1

Because Ca has a charge of 2+ and S has a charge of 2-, so if you cross multiply those charges you get Ca2S2, which can simplify to CaS, a 1:1 ratio.

…S does not have a charge of 3-

**Answer 2**

none of the above.

ionic charge of Ca is +2, S is -3

you might be missing information