Let's assume the initial quantity of water and acid = \(X\) grams.
Second test tube = \(X + 20\) grams (20 g Acid)
= \(\frac{2}{3} × (X + 20) = \frac{2}{3}X + \frac{40}{3}\)
= \(X + \frac{2}{3}X + \frac{40}{3} = 4 × \frac{1}{3}(X + 20)\)
= \(X + \frac{2}{3}X + \frac{40}{3} = \frac{4}{3}(X + 20)\)
On multiplying we get,
= \(3X + 2X + 40 = 4(X + 20)\)
= \(5X + 40 = 4X + 80\)
= \(X = 80 - 40\)
\(X = 40\) grams
The correct option is (C): 40 grams