Question

“The importance of many pure substance in life depends on their composition.” Which of the following statement justify the above fact?

विकल्प

• 1 ppm of fluoride ions in water prevents tooth decay.

• 1.5 ppm of fluoride ions causes tooth decay.

• Concentration above 1.5 ppm can be poisonous.

• All of the above.

Answer 1

All of the above.