Multiple choice

A beaker had citric acid and some water mixed in it in the ratio of 4 : 1. 10 ml of the solution is taken out 10 ml of water is poured into it. The present ratio of the citric acid and water is 2 : 3. How much citric acid was present in the glass in the beginning?

  1. 4 ml

  2. 8 ml

  3. 16 ml

  4. 40 ml

  5. 42 ml
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let initial acid be 4x and water be x. Total = 5x. After removing 10ml, acid = 4x - 8, water = x - 2. Adding 10ml water: acid = 4x - 8, water = x + 8. Ratio (4x-8)/(x+8) = 2/3. 12x - 24 = 2x + 16, 10x = 40, x = 4. Initial acid = 4*4 = 16 ml.

AI explanation

Let the initial volumes of citric acid and water be 4X and X, making the total initial volume 5X. Removing 10 ml of solution takes out 8 ml of citric acid and 2 ml of water, leaving 4X minus 8 ml of acid and X minus 2 ml of water. Adding 10 ml of water makes the new ratio (4X minus 8) to (X plus 8) equal 2 to 3, which results in 12X minus 24 equaling 2X plus 16, so X is 4. Since the original acid was 4X, the initial amount of citric acid was 16 ml.

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