Rekha filled her beaker with 40ml of a 75% solution of hydrochloric acid. Her chemistry teacher pointed out that she should have 40 ml of a 50% hydrochloric acid solution. Jane drains x ml from her beaker and replaces with x ml of water to get the proper solution. In which of the following ranges does x lie?


A) less than 5
B) at least 5, but less than 10
C) at least 10, but less than 15
D) at least 15, but less than 20
E) 20 or more

• option C is the correct answer (At least 10,but less than 15)
  
  75%hcl means that in 100gm water 75gm is HCL.
  So in 40 ml water the HCL is 30gm HCL and 10gm water
  But the teacher wants to make it as 20gm HCL and 20gm water.
  
  So if she replaces 5ml,then still there will be 26.25 gm HCL in beaker(Incorrect)
  Now if she replaces 10ml atleast,there will be 22.5 gm HCL in beaker (Incorrect)
  So now if she replaces 15ml then ther will be 17.5gm HCL in beaker. So now she can add dilute HCL to make it 50 %
  
  
  option C is the correct answer (At least 10,but less than 15)
  
• 12 years agoHelpfull: Yes(3) No(2)
• 
  
  C) at least 10, but less than 15
• 12 years agoHelpfull: Yes(2) No(2)