AP EAMCET202021 Sep 2020Evening ShiftChemistrySome Basic Concepts of ChemistryActual
Calculate the concentration of fluorine in ppm in (500 ~g ) of toothpaste containing (0.2 ~g ) of fluorine.
Options
- A(2 10^2 )
- B(4 10^2 )
- C(4 10^0 )
- D(4 10^3 )
Correct answer
B. (4 10^2 )
Step-by-step solution
PPM or Parts Per Million is expressed as 1 milligram of substance per kilogram of parent substance. Since, mass of toothpaste (=500 ~g =0.5 ~kg ), and mass of fluoride ion (=0.2 ~g =200 mg , 0.5 ~kg ) toothpaste contains (200 mg ) fluoride ions, (1 ~kg ) toothpaste will contain (200 2=400 mg ) fluoride ions. Hence, concentration of fluoride ion is (400 ppm ) or (4 10^2 ppm ). Hence, option (b) is correct.