Dilutions / Pengenceran

If 400 mL of a 20% w/v solution were diluted to 2 liters, what would be the per­centage strength (w/v)?

• 4% w/v

• 8% w/v

• 0,4% w/v

• 40% w/v

How many milliliters of a 1: 50 w/v boric acid solution can be prepared from 500 mL of a 5% w/v boric acid solution?

• 1250 mL boric acid solution

• 125 mL boric acid solution

• 50 mL boric acid solution

• 1,25 mL boric acid solution

If a pharmacist added 12 g of azelaic acid to 50 g of an ointment containing 15% azelaic acid, what would be the final con­centration of azelaic acid in the ointment?

• 31,5% w/w

• 3,15% w/w

• 315% w/w

• 0,315% w/w

How many milliliters of water must be added to 250 mL of a 25% w/v stock solu­tion of sodium chloride to prepare a 0.9% w/v sodium chloride solution?

• 6694,4 mL water

• 6944,4 mL water

• 669,44 mL water

• 66,944 mL water

How many milliliters of undecylenic acid would need to be added to 30 mL of a 20% undecylenic acid topical solution to change its concentration to 25%?

• 2 mL undecylenic acid

• 3 mL undecylenic acid

• 4 mL undecylenic acid

• 5 mL undecylenic acid

How many grams of zinc oxide should be added to 3400 g of a 10% zinc oxide ointment to prepare a product containing 15% of zinc oxide?

• 200 g zinc oxide

• 150 g zinc oxide

• 2200 g zinc oxide

• 240 g zinc oxide

How many grams of salicylic acid should be added to 75 g of a polyethylene glycol ointment to prepare an ointment contain­ing 6% w/w of salicylic acid?

• 4,787 g salicylic acid

• 45 g salicylic acid

• 4,5 g salicylic acid

• 47,87 g salicylic acid

How many milliliters of water should be mixed with 1200 g of 65% w/w alcohol to make 45% w/w alcohol?

• 533 mL water

• 173 mL water

• 830 mL water

• 273 mL water

How many milliliters of a syrup contain­ing 85% w/v of sucrose should be mixed with 150 mL of a syrup containing 60% w/v of sucrose to make a syrup containing 80% w/v of sucrose?

• 600 mL syrup

• 150 mL syrup

• 105 mL syrup

• 112 mL syrup

How many milliliters of a 0.2% solution of a skin-test antigen must be used to pre­pare 4 mL of a solution containing 0.04 mg/mL of the antigen?

• 0,08 mL antigen

• 0,8 mL antigen

• 8 mL antigen

• 80 mL antigen