Question

What is the total number of ions present in the formula Na2SO4?

A. 2
B. 3
C. 4
D. 6

The answer given is B. 3, why?

Answer 1

The answer should be 3 ions.

Explanation:

After looking again it seems to me that the number of ions in one molecule are actually just Na, S and O, which means 3 ions.
`color (red)"What you mentioned Na, S and O are three elements in the"` `color (red)"given compound."`
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.

Given compound is `"Na"_2"SO"_4`
If one breaks up the given compound in its constituent ions one obtains
`2" cations of sodium, Na"^+` and `1" anion as sulfate, SO"_4^(2-)`

`:.`Total 3 ions.

Answer 2

Let's see how it behaves in water.

Explanation:

`Na_2SO_4 -> 2 Na^+ + SO_4^2-`
So it's free ions.