A chemical supply company has 60 liters of a 30% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?
Select.
A) 12 B) 15 C) 20 D) 24 E) 30
60 liters of a 30% HNO3 solution means HNO3 = 18 liters in 60 liters of the solution.   Now, let x be the pure HNO3 added.   As per question,   18 + x = 50% of (60 + x)   or x =24. Hence, 24
<result>D</result>
A chemical supply company has 60 liters of a 30% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?