we have,

$N=0.1$

volume $(L)=200 \,ml / 1000=0.2 \,L$

no of moles $=$ volume $x$ normality

$=0.2 \times 0.1=0.02$ moles

we know,

$1\, mole$ of $Ag =96500 \,C$

so, $0.02\,moles=0.02 \times 96500=1930 \,C$

we know $q= it ( q=$ charge, $i=c u r r e n t, t=$ time $)$

$1930=0.1 \times t$

$t=19300$ second

now, time taken to remove half the silver from solution $= t / 2=19300 / 2$

$=9650\, seconds$ (Answer)