Prove that
Moment of couple= Force `times` couple arm

Answer

355

Explanation

`Pb^(2+)+2e^(-)toPb` ltbr `E_(Pb^(2+)//Pb)^(0)=E_(Pb^(2+)//Pb)^(0)-(0.0591)/(2)log((1)/(0.1))=-0.1555"volt"`
`E_(cell)=E_(Pb^(2+)//Pb)-E_(Tl^(+)//Tl)`
`E_(Tl^(+)//Tl)-0.5985V`
`Tl^(+)+e^(-)toTl`
`E_(Tl^(+)//Tl)=E_(Tl^(+)//Tl)^(0)-0.059log((1)/((Tl^(+))))`
`-0.5985=-0.336+0.059log((Tl^(+))`
`Tl^(+)=3.55xx10^(-5)M`
`KsP=[Tl^(+)][Br^(-)]=3.55xx10^(-5)xx0.1=3.55xx10^(-6)M^(2)=355xx10^(-8)M^(2)`