Step1 mass of 1 litre of sea water = 1.025x1000 =1025 g Step2 mass of iodine = 60x10^-9 x 1025 g Step3 Atomic mass of iodine =126.90447 Step4 Molarity of I- ion = (60x10^-9 x1025)/126.90447 = 4.846x10^-7= 4.8x10^-7 M Step5 Option B is correct Solution Step1 mass of 1 litre of sea water = 1.025x1000 =1025 g Step2 mass of iodine = 60x10^-9 x 1025 g Step3 Atomic mass of iodine =126.90447 Step4 Molarity of I- ion = (60x10^-9 x1025)/126.90447 = 4.846x10^-7= 4.8x10^-7 M Step5 Option B is correct.