Multiple choice

A chemist has 10L of a solution that is 10% nitric acid by volume. He wants to dilute the solution to 4% strength by adding water. How many litres of water must be add? एक रसायनज्ञ के पास 10L का घोल है जिसमे कि मात्रा का 10% नाइट्रिक एसिड है। वह पानी को जोड़कर मिश्रन को 4% तक करना चाहता है। कितने लीटर पानी जोड़ना होगा?

  1. 40

  2. 33

  3. 25

  4. 15

  5. 20
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Initial solution: 10L with 10% nitric acid means 1L acid, 9L water. Let x liters of water be added. New volume = 10 + x liters. Acid volume remains 1L. We need 1/(10 + x) = 0.04. Solving: 1 = 0.04(10 + x), 1 = 0.4 + 0.04x, 0.6 = 0.04x, x = 0.6/0.04 = 15. So 15L of water must be added.

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