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[tex]\huge\underline\mathtt\colorbox{cyan}{B. 100 ml of water}[/tex]
10 gm salt in 100 ml water- let its concentration be x
We want 2x(A. T. Q)
For decreasing concentration, we need higher solvent(water here)
x= 100ml
2x=2(100)ml
We already had 100 ml
So 200-100=100
100ml is correct