The answer is 2.42 ml (milliliter)
Determine the balanced equation:
Balanced equation = NA2S (aq) + 2 AGNO3 (aq) ----> 2NANO3(aq) + AG2(s)
Let:
Number of moles of AGNO3 = AGNO3 * vol. of AGNO3
Substitute values:
number of moles = 0.315 * 0.04
number of moles = 0.0126 AGNO3
(For NA2s)
Let:
Number of moles of NA2s = 1/2 (number of moles of AGNO3)
number of moles of NA2s = 0.0063
volume of NA2s needed = number of mole of NA2s / NA2s
For the volume:
Volume = 0.0063 / 0.260
thus,
V = 0.02423 L (should be converted to milliliter)
Therefore the Volume in ml = 2.42 ml (milliliter)