fluorosilicic acid is the inorganic compound with the formula H2SiF6 Moles of acid =10^-3/144.09 =6.94*10^-6 See 1 mole of acid has 6 mole of fluoride ions in the formula So Increase in concentration = 6*6.94*10^-6/V =4.164*10^-5/V You haven\'t given volume of water. Put V and get concentration. Solution fluorosilicic acid is the inorganic compound with the formula H2SiF6 Moles of acid =10^-3/144.09 =6.94*10^-6 See 1 mole of acid has 6 mole of fluoride ions in the formula So Increase in concentration = 6*6.94*10^-6/V =4.164*10^-5/V You haven\'t given volume of water. Put V and get concentration..