A chemical supply company has 60 liters of a 35% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?  Choose one:  A) 18  B) 15  C) 20  D) 24  E) 30
60 liters of a 35% HNO3 solution means HNO3 = 21 liters in 60 liters of the solution.   Now, let x be the pure HNO3 added.   18s per question,   21 + x = 50% of (60 + x)   or x =18 Hence, 18
<result>A</result>
A chemical supply company has 60 liters of a 35% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?