Which of the following statements `is//are` correct ?

Options

A. Mass of `Al_(2) (SO_(4))_(3).18H_(2) O` needed to make up `100 mL` of an aqueous solution of concentration `27.0 mg` of `Al^(3+)` per `mL` is `33.3 g`
B. Mass of `CrCl_(3).6H_(2)O (Mw = 266.5 g)` needed to prepare `1.0 L` solution containing `26.0 g Cr^(3+)` per litre is `133.25 g`. (Atomic weight of `Cr = 5 g`)
C. Mass of `NH_(4) Cl` needed to prepare 100ml for solution containing `80 mg` `NH_(4)Cl` per `mL` is `8.0 g`
D. Mass of `NH_(3)` per `mL` of solution needed for solution of `NH_(3)` in water containing 20% `NH_(3)` by weighter (density `= 0.8 g mL^(-1)_` is `0.16 g mL^(-1)`

Answer

A, B, C, D

Explanation

a. Weight `g Al^(3+)` in `100 mL` of solution `= 100 xx 27`
`= 2700 mg = 2.7 g`
1 mol `Al^(3+) (27 xx 2 g) -= 1 "mol of" Al_(2) (SO_(4))_(3) . 18 H_(2) O`
`2 "mol" Al^(3+) (27 xx 2 g) -= 1 "mol of" Al_(2) (SO_(4))_(3). 18 H_(2) O`
`= 666 g`
`2.7 g "of" Al^(3+) = (666 xx 2.7)/(54) = 33.3 g`
b. moles of `Cr^(3+) = (26)/(52) = 0.5 "mol"`
Weight of `CrCl_(3). 6H_(2)O = 0.5 "mol" Cr^(3+) xx 266.5 g`
`= 133.25 g`
c. Weight of `NH_(4) Cl = (100 mL) ((80 mg)/(mL))((10^(-3) g)/(mg)) = 8.0 g`
d. Weight of `NH_(3) = ((0.8 g)/(mL "solution"))((20 g NH_(3))/(100 g solution))`
`= 0.16 g mL^(-1)`