Question

How much pure alcohol must be added to 400 ml of a 15% solution to make its strength 32%​

Answer 1

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How much pure alcohol must be added to 400 mL of a 15% solution to make its strength 32%.

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Hint: In this question, the concept of percentages will be used. The relation between the percentage and the amount of substance in a mixture is given by-

VolumeofdissolvedsubstanceTotalvolumeofliquid×100=percentage

Complete step-by-step solution -

Now, we have been given that initially 15% of alcohol is present in a 400 mL solution. We will first find the volume of alcohol in the initial solution using the formula. Let the amount of alcohol be v mL, then-

v400×100=15

v = 60 mL

This is the initial amount of alcohol. Now, let us assume that x mL of alcohol is added to the solution. The new volume of alcohol will be 60+x and the new volume of solution will be 400+x. It is given that the strength of this solution is 32%. So, the equation formed will be-

60+x400+x×100=32

⇒60+x=0.32(400+x)

⇒60+x=128+0.32x

⇒0.68x=68

⇒x=100mL

Therefore, 100 mL of alcohol should be added to make the strength 32%. This is the required answer.

Answer 2

Answer:

How much pure alcohol must be added to 400 mL of a 15% solution to make its strength 32%?

Solution:-

Therefore, 100 mL of alcohol should be added to make the strength 32%. This is the required answer.

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