CBSE Class 10 Answered

Dear Meghapte,

Let us say you are using  x Lt of  50% acid and (10-x )Lt of 25% acid to make  10 Lt  of 40% acid.

Usually lab people used to mix distilled water to concentrated acid to make it di

Acid content in final solution = 10 X (40/100)  =4 Lt.

Similarly Acid in 1 Lt solution of 50% acid=  1X (50/100) = 0.5 Lt

                Acid in 1 Lt solution of 25% acid=  1X (25/100) = 0.25 Lt

So      x  ( 0.5)   +   (10-x) 0.25      =     10 X  0.4

                0.5 x   +    2.5 - 0.25 x   =       4

                0.25 x =  4 - 2.5 = 1.5 

               x= 1.5 / 0.25 = 6

 6 Lt of  50% acid  and  4 Lt (i.e 10-6)   of 25% acid are needed to make  10 Lt of 40% acid.

Regards

Topperlearning team.