# Civil Engineering - GATE Exam Questions - Discussion

### Discussion :: GATE Exam Questions - Section 4 (Q.No.5)

5.

In a BOD test, 5 ml of waste is added to 295 ml of aerated pure water. Initial dissolved oxygen (D.O) content of the diluted sample is 7.8 mg/l. After 5 days of incubation at 20°C, the D.O. content of the sample is reduced to 4.4 mg/l. The BOD of the waste water is :

 [A]. 196 mg/l [B]. 200 m/l [C]. 204 mg/l [D]. 208 mg/l

Explanation:

No answer description available for this question.

 Jay Shah said: (Feb 4, 2015) BOD = (INITIAL-FINAL)*300/ML. = (7.8-4.4)*300/5 = 204 MG/L.

 Nayan Kulkarni said: (Jun 4, 2015) BOD = (DO initial -DO final)*Dilution factor. = (7.8-4.4)*(295/5). = 200.6 mg/lit

 Divya Vishnoi said: (Apr 29, 2016) BOD = (initial D.O - Final D.O.)* Dilution factor. = (7.8 - 4.4)*300/5. = 204 mg/l.

 Priyanka said: (Mar 25, 2017) The correct answer is 204.

 Erick said: (Jun 8, 2017) The first initial DO of the mixture is required. DO = 7.8 x (295/300) = 7.67, BOD = (7.67-4.4)/(5/300) = 196.2 mg/L.

 Himanshu said: (Nov 16, 2017) BOD = (initial D.O - Final D.O.)/ Dilution factor. = (7.8 - 4.4)/(5/300). = 204 mg/l.

 Keshav Kaushik said: (Jan 9, 2019) Dilution Factor = volume of wastewater sample/(volume of wastewater sample + dilution sample). B.O.D = Initial D.O - Final D.O / dilution factor = 204mg/l.

 Manisha Nimje said: (Jan 9, 2020) The correct answer is 204 mg/l.

 Sachin S Naik said: (Jan 30, 2020) The correct answer is 200.6mg/l.

 Abhishek said: (Sep 7, 2021) Df = 295รท5 Bod = (intial Do-final DO) * D.F, = 200.6.

 Abhishek Thakur said: (Sep 10, 2021) The volume of dilution sample over the undiluted raw sample is a formula not aerated water over an undiluted raw sample. 204 is the right answer.

 Abhishek Thakur said: (Sep 10, 2021) The volume of dilution sample over the undiluted raw sample is a formula not aerated water over an undiluted raw sample. 204 is the right answer.

 Sharath Manohar said: (Nov 26, 2021) 295/5 * (7.8-4.4) = 200 mg/l is the actual right answer.

 Lencho Edeto said: (May 19, 2022) BOD = [DO( initial) -DO final)] * Dilution factor. = (7.8-4.4)mg/lit * (295/5). = 200.6 mg/lit.