Answer : The molar concentration of phosphate ions in lithium phosphate solution is, 0.350 M
Explanation : Given,
Concentration of lithium phosphate = 0.350 M
As lithium phosphate dissolve in water, it dissociates into lithium ions and phosphate ions.
The balanced reaction will be,

From the balanced reaction we conclude that,
As, mole ratio of
,
and
is, 1 : 3 : 1
So,
The molar concentration of lithium ion = 3 × 0.350 M = 1.05 M
The molar concentration of phosphate ion = 0.350 M
Therefore, the molar concentration of phosphate ion is, 0.350 M