9
Answer: DSet 3: Linear Equations (Advanced)
Explanation
A chemist has 100 mL of a 40% acid solution. How many mL of pure acid must be added to create a 60% acid solution?
How many mL of pure acid should be added?
A.
40
B.
30
C.
60
D.✓ Correct
50
Detailed Explanation
Choice D is correct. Initial acid: 0.40(100) = 40 mL. After adding x mL pure acid: (40 + x)/(100 + x) = 0.60. Cross multiply: 40 + x = 0.60(100 + x) = 60 + 0.60 x. So 0.40 x = 20, x = 50.
Key Steps:
•
The correct answer is 50
Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
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