Correct Answer - Option 3 : Only c
Given∶
A sample of 60L of concentrated acid is found to be diluted to the extent of 40%.
Formula Used∶
Basics of percentage.
Calculation∶
A sample of 60L of concentrated acid is found to be diluted to the extent of 40%
Amount of dilution in acid = 40% of 60
⇒ 40/100
× 60 = 24 L
The amount of pure acid = 60 - 24 = 36 L
Let 'a' be the amount of pure acid added to it so as to bring down the percentage of impurity to 5%.
New amount of Acid = 60 + a
Amount of pure acid = 36 + a
Required amount of pure acid = 95% of (60 + a)
⇒ 0.95
× (60 + a) = 57 + 0.95a
Now,
36 + a = 57 + 0.95 a
⇒ a = 420 L
So, statement 'c' is correct.
∴ 420 L pure acid is to be added. So, the correct option is 3 (Only c).