Multiple choice

A chemist has 10 ml of a solution that contains 30% concentration of acid. What amount (in millilitres) of pure acid is to be added to the solution, to increase the concentration to 50%?

  1. 4

  2. 3

  3. 2

  4. 1
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A Correct answer
Explanation

Initial acid = 10 * 0.3 = 3 ml. Let x be the amount of pure acid added. (3 + x) / (10 + x) = 0.5. 3 + x = 5 + 0.5x. 0.5x = 2. x = 4.

AI explanation

The initial 10 ml solution contains 3 ml of acid and 7 ml of water. Let x ml of pure acid be added to achieve a 50 percent concentration, resulting in the equation (3 + x) divided by (10 + x) equals 0.5. Solving this equation gives 3 + x equals 5 + 0.5x, which simplifies to x equals 4.

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