(6.a) 0.0001 g

This is the correct moles of CaSO₄

CaCl₂(aq) + Na₂SO₄(aq) ---> CaSO₄(s) + 2 NaCl(aq)

CaCl₂(aq) 0.0001 moles (limiting reagent) and
Na₂SO₄(aq) 0.0002 moles (excess reagent)

Note: that the precipitate will require equal numbers of moles of Ca⁺² and SO₄^-2. If one of the species is present in smaller amounts you will deplete it first and it will be the limiting reagent and will determine the amount of precipitate that can be formed.

0.0001 moles of calcium sulfate will be produced since calcium chloride is the limiting reagent.

0.0001 moles of CaSO₄ x (136 g CaSO₄ /1 mole CaSO₄) = 0.01g calcium sulfate