Well diameter = 2 m

Water depth = 6 m

Volume of water in the well = 3.14 x d2 x h

                                                         4

                                                =3.14 x 22 x 6

                                                           4

                                                           = 18.84 m3

1m3 = 1000 l

So 18.84 m3 = 18840 litres

Amount of bleaching powder required as per Horrock’s apparatus = 8 g for 455 litres

So for 18840 litres, bleaching powder required is 8 x 18840   = 331.25 g

                                                                                   455