find moles, using molar mass:
2.71 g ZnCl2 @ 136.32 g ZnCl2 / mole = 0.01988 moles Zn+2
find moles
0.350.L @ 0.0560 moles / Litre = 0.0196 moles (CO3)-2
by the equation
Zn+2 & CO3)-2 --> ZnCO3 (s)
0.0196 moles (CO3)-2 reacts with an equal 0.0196 moles Zn+2 ,
0.01988 moles Zn+2 - 0.0196 moles Zn+2 reacted = 0.00028 moles Zn+2 remain
find molarity remaining
0.00028 moles Zn+2 / 0.350 litres = 0.000799 Molar
your answer, to 1 sig fig is
0.0008 Molar Zn+2
aka
0.8 milliMolar Zn+2
