Answer:
The right solution according to the question is provided below.
Step-by-step explanation:
According to the question,
(a)
The initial conditions will be:
DO =

=

=

The initial oxygen defict will be:
Do =

=

The initial BOD will be:
Lo =

=

=

(b)
The time reach minimum DO:
tc =
![(1)/((kr-kd)) ln{((0.76)/(0.61) )[1-(1.674(0.76-0.61))/(0.61* 6.453) ]}](https://img.qammunity.org/2022/formulas/chemistry/college/tfqroqzrawmraqn1dx8q2sb3voxqf91ba7.png)
=

By putting the values of log, we get
=

The distance to reach minimum DO will be:
Xc =

=

=
