Cleaning is done by (i) Scraping and removal in filters slow sand (ii) Back washing in slow sand filters (iii) Scraping and removal in filters rapid sand (iv) Back washing in rapid sand filtersThe correct answer is

Cleaning is done by
(i) Scraping and removal in filters slow sand
(ii) Back washing in slow sand filters
(iii) Scraping and removal in filters rapid sand
(iv) Back washing in rapid sand filters
The correct answer is

A

(i) and (ii)

B

(ii) and (iii)

C

(i) and (iv)

D

(ii) and (iv)

Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.
Reason R: The sand used in slow sand filters is finer than that in rapid sand filters
Select your answer based on the coding system given below:

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true but R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.Reason R: The sand used in slow sand filters is finer than that in rapid sand filtersSelect your answer based on the coding system given below:

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true but R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

Which of the following statements are correct pertaining to the value of uniformity coefficient Cu for filter sand? (1) For slow sand filters, Cu = 1.8 to 2.5 (2) For rapid sand filters, Cu = 1.3 to 1.7 (3) For slow sand filters, Cu = 1.3 to 1.7 (4) For rapid sand filters, Cu = 1.8 to 2.5

A

2 and 3

B

1 and 4

C

3 and 4

D

1 and 2

Consider the following statement. i. Slow sand filter is not flexible in variation in demand ii. The rapid sand filter is flexible in fluctuations in demand iii. The method of cleaning of a slow sand filter involves agitation and back-washing Which of the above statement is/are correct?

A

i, ii

B

i, ii, iii

C

ii, iii

D

Only iii

Consider the following statements in respect of slow sand filter and rapid sand filter: 1. The two filters differ in respect of the standards regarding the non-uniformity of the sand used in their filtering media. 2. The two filters do not differ in respect of the effective size of the sand used in them. 3. The two filters differ in respect of their respective under-drainage system. 4. The two filters differ in respect of their respective rate of filtration. Which of the above statements are correct?

A

1, 2 and 3

B

1, 2 and 4

C

2, 3 and 4

D

1, 3 and 4

As compared to rapid sand filters, slow sand filters give (i) Slower filtration rate (ii) Higher filtration rate (iii) Lesser efficiency in removal of bacteria (iv) Higher efficiency in removal of bacteria The correct answer is

A

(i) and (ii)

B

(ii) and (iii)

C

(i) and (iv)

D

(ii) and (iv)

As compared to rapid sand filters, slow sand filters give
(i) Slower filtration rate
(ii) Higher filtration rate
(iii) Lesser efficiency in removal of bacteria
(iv) Higher efficiency in removal of bacteria
The correct answer is

A

(i) and (ii)

B

(ii) and (iii)

C

(i) and (iv)

D

(ii) and (iv)

The Northern Railways has installed an automatic train washing plant at Hazrat Nizamuddin station in Delhi. The washing system has a capacity of 250 coaches per day and takes 7-8 minutes to wash a 24-coach rake, thus saving water used for cleaning. Which of the following could be the cause of the statement? I: The automatic system will use 6000 liters of which 4000 liters will be recycled water, thus saves water used for cleaning. II: It would be eco-friendly as it uses the minimum quantity of water, soap, and disinfectants. III: As per the calculations, one depot will save 1,24,000 liters of water per day and 453 lakh liters per year after the plant is operational.

A

Only I

B

Only II and III

C

Only I and II

D

Only I and III

E

All of these

Consider the following statement. i. The penetration of suspended matter is deep in the slow sand filter ii. The penetration of suspended matter is superficial in the rapid sand filter iii. Coagulation is not required in the slow sand filter Which of the above statement is/are correct?

A

Only iii

B

i, ii

C

i, ii, iii

D

ii, iii

Cleaning is done by (i) Scraping and removal in filters slow sand (ii) Back washing in slow sand filters (iii) Scraping and removal in filters rapid sand (iv) Back washing in rapid sand filtersThe correct answer is

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