Answer:
0.6941 mg
Explanation:
First we calculate how many LiNO₃ moles there are, using the given concentration and volume:
As 1 mol of LiNO₃ contains 1 mol of Li, in the problem solution there are 0.10 mmol of Li (the only metallic ion present).
Now we convert Li milimoles into miligrams, using its atomic mass: