A50.0 −ml sample of 1.50×10−2 m na2so4(aq) is added to 50.0 ml of 1.28×10−2 m ca(no3)2(aq). what percentage of the ca2+ remains unprecipitated?

When we have Ksp CaSO4 = 9.1x10^-6 so by substitution in Ksp formula:
Ksp CaSO4 = [Ca+2][SO4] 
1.9x10^-6   = [Ca+2][1.5x10^-2]
∴ [Ca+2] M in the solution =1.27x10^-4
when percent remaining = [Ca in solution]/[C original value] * 100
                                          = [(1.27x10^-4*(50ml+50ml)]/[1.28x10^-2*50ml]*100
                                          ≈ 2%

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.