Answer:
The final concentration in test-tube 3 is = 4ug/mL
Explanation:
Dilution factor = V initial / V final
Concentration of Stock solution = 500 ug/mL
5 test tubes are prepared with 4 mL of water
1 ml of stock solution is added to the 1st test tube.
therefore, the total volume of 1st test tube is = 4 ml + 1 ml = 5ml
∴ the concentration of 1st Test tube →
C = m/V [m= mass (solute) , v= volume]
=500 ug / 5 ml = 100 ug/ml
From 1st test tube, 1 ml is taken out and that is added to the 2nd test tube.
∴ the concentration of 2nd Test tube = 100 ug / 5ml
= 20 ug/ml
From 2nd test tube, 1 ml is taken out and that is added to the 3rdd test tube.
∴ the concentration of 3rd Test tube = 20 ug / 5ml
= 4 ug/ml
The final concentration in test-tube 3 is = 4ug/mL
