18. Calculate the concentration of chromate ion, CrO42–, in a saturated solution of CaCrO4 (Ksp= 7.1 × 10–4).(A) 2.7 × 10–2 M(B) 3.5 × 10–2 M(C) 7.1 × 10–4 M(D) 3.5 × 10–4 M(E) 5.0 × 10–7 M