bhumika.k.shah wrote:I am sowree but i dint quite understand...
could u break it down step by step or explain using #s...As i am quite comfortable using #s than equations
A 50% acid is acid diluted with water - 50% pure concentrated acid and rest water. In other words, 100 ml of the 50% acid contains 50 ml of 100%concentrated acid.
Similarly a 30% acid contains 30% acid and rest water. 100 ml of the 30% acid contains 30ml of 100%concentrated acid.
Plugging the answers .....
A.
Now if take 1/5 out of first mix - 80 ml of 50% acid remains and 40 ml of it is pure concentrated acid
if you replace it with 20 ml of 30% acid which contains 6 ml of pure concentrated acid
Now the the mixture contains 40+6 = 46 ml of concentrated acid in 100 ml hence is a 46% acid. but, you wanted to obtain 40% acid hence A is not the answer
B. 75 ml of 50% acid contains - 37.5ml of pure acid
25 ml of 30% acid contains - 7.5 ml of pure acid
Mixture contains - 45ml of pure acid in 100 ml hence 45%
C. 50 ml of 50% acid - 25 ml
50 ml of 30% acid - 15 ml
Mixture contains - 40 ml of pure acid in 100 ml hence 40%. The answer you are looking for....
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