Concentration of `SO_(4)^(2-)` ions in a solution prepared by mixing `100 ml 0.1 M BaCl_(2)` and `400 ml 0.2 M Na_(2)SO_(4)`.

Options

A. `(8)/(50)M`
B. `(7)/(50)M`
C. `(7)/(40)M`
D. `(1)/(25) M`

Answer

B

Explanation

`{:(BaCl_(2),+,Na_(2) SO_(4),rarr,BaSO_(4),+,2NaCl,),(0.01 "mole",,0.08 "mole",,,,,),(-,,0.07 "mole",,underset(PPt darr)(0.01 "mole"),,0.01 "mole",):}`
`{:(Na_(2)SO_(4),rarr,2Na^(+),+,SO_(4)^(2-),),(0.07 "mole",,-,,-,),(-,,0.14 "mole",,0.07 "mole",):}`
`[SO_(4)^(2-)] = (n_(SO_(4)^(2-)))/(V_(1) + V_(2)) = (0.07)/(0.5) = (7)/(50) M`