Generic selectors
Exact matches only
Search in title
Search in content
Search in posts
Search in pages
Filter by Categories
nmims post
Objective Type Set
Online MCQ Assignment
Question Solution
Solved Question
Uncategorized

Multiple choice question for engineering

Set 1

1. The depth of an enclosed tank of a rapid sand filter lies in the range of ______
a) 1-2m
b) 2.5-3.5m
c) 2-5m
d) 3-5m

View Answer

Answer: b [Reason:] The depth of an enclosed tank of a rapid sand filter lies in the range of 2.5-3.5m and its surface area lies between 20-50m2.

2. The effective size of a rapid sand filter is ______
a) 0.45mm
b) 0.7mm
c) 0.8mm
d) 0.9mm

View Answer

Answer: a [Reason:] The effective size of a rapid sand filter lies in the range of 0.35-0.6mm and its common value is 0.45mm.

3. The finer the suspended impurities to be removed,
a) Larger will be the sand size
b) Smaller will be the sand size
c) Smaller will be the surface area of sand grains
d) Narrow will be the sand depth of the bed

View Answer

Answer: b [Reason:] The finer the suspended impurities to be removed, smaller will be the sand size in order to increase the surface area of sand grains in the sand bed.

4. What is the value of uniformity coefficient in a rapid sand filter?
a) 1
b) 1.5
c) 2
d) 2.5

View Answer

Answer: b [Reason:] The value of uniformity coefficient in a rapid sand filter lies between 1.2 and 1.7 and its common value is 1.5.

5. What is the effective size of Anthracite when used as a filter material?
a) 0.1-0.2mm
b) 0.2-0.4mm
c) 0.4-0.6mm
d) 0.7-0.75mm

View Answer

Answer: d [Reason:] The effective size of Anthracite when used as a filter material lies between 0.7-0.75mm and its uniformity coefficient is 1.75.

6. Consider the following statement regarding depth of sand of the rapid gravity filter?
1. It should be checked against breakage of floc
2. The sand depth should lie between 100-200cm
3. The floc should be attached through the sand bed
Which of the above statement is/are correct?
a) Only 1
b) 1, 2
c) 2, 3
d) Only 2

View Answer

Answer: a [Reason:] Sand depth should be such that floc do not break through the sand bed and the depth of sand should vary between 60-90 cm.

7. Which of the following statement is wrong regarding Anthracite?
a) It requires less water
b) It is less inert to caustic solutions than sand
c) It is more costly per tonne than sand
d) It is used in industrial filters.

View Answer

Answer: b [Reason:] Anthracite is a costlier filter material used in industrial filter which is more inert to hot caustic solutions than sand.

8. The minimum depth of sand of a rapid sand filter is given by
a) Stokes formula
b) Clark’s formula
c) Hudson formula
d) Emden formula

View Answer

Answer: c [Reason:] The minimum depth of sand of a rapid sand filter is given by Qd3h/l=B*29323, Where Q=filtration rate, d =sand size, H= head loss, l=depth of sand bed, B=break through index.

9. The thickness of the base material of a rapid sand filter on which filter media are supported is
a) 45-60cm
b) 20-80cm
c) 30-75cm
d) 10-30cm

View Answer

Answer: a [Reason:] The base material of a rapid sand filter consists of 45-60 cm thick gravel bed which is laid in layers of 15 cm with finer topmost layer (2-6mm) and coarser bottom layer (20-50mm).

10.In which type of under drainage system of rapid sand filter, laterals are provided with strainers?
a) Perforated pipe system
b) Pipe and strainer system
c) Wheeler system
d) Wagner system

View Answer

Answer: b [Reason:] In Perforated pipe system, laterals are provided with strainers. Strainers are made of brass or bronze and are in umbrella shape, having a small perforation. They distribute the wash water without jet action.

11.Which device is used to supply air for the agitation of sand grains during washing of filters?
a) Rate control device
b) Tube settlers
c) Air compressors
d) Flocculator

View Answer

Answer: c [Reason:] Air compressor is used to supply air for the agitation of sand grains at the rate of 0.6-0.8m3 per minute per m2 of filter area for 5 minutes.

Set 2

1. The reciprocating pump has a ______ flow.
a) Pulsating
b) Uniform
c) Continuous
d) Constant

View Answer

Answer: a [Reason:] The reciprocating pump has a continuous flow. It has a constant discharge even if head on the delivery side varies.

2. The speed at which the reciprocating pump runs (in m/min) is
a) 28
b) 90
c) 100
d) 120

View Answer

Answer: a [Reason:] The reciprocating pump runs at low speed. Its speed is less than 30m/min. If they are connected to driving machines, speed reducing devices is necessary.

3. The maximum efficiency of a reciprocating pump is
a) 50%
b) 60%
c) 85%
d) 100%

View Answer

Answer: c [Reason:] The efficiency of the reciprocating pump lies between 40% and 85%. Long stroke engines have 85% efficiency while smaller pumps have 40%.

4.In which type of pump, the liquid is in contact with both sides of the plunger?
a) Single acting reciprocating pump
b) Double acting reciprocating pump
c) Single cylinder pump
d) Booster pump

View Answer

Answer: b [Reason:] At the double acting reciprocating pump, the liquid is in contact with both sides of the plunger. It has two suction and deliver pipes having appropriate valves.

5. Based on the number of cylinders, the reciprocating pump is divided into ____ types.
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: d [Reason:] the reciprocating pump is divided into 5 types on the basis of number of cylinders. It includes single cylinder, double cylinder, triple cylinder, duplex double action and quintuplex pump.

6. Which type of reciprocating pump has a 1200 crank?
a) Single cylinder pump
b) Double cylinder pump
c) Triple cylinder pump
d) Duplex double action pump

View Answer

Answer: c [Reason:] In a Triple cylinder reciprocating pump, each cylinder has its own suction and delivery pipes and has a 1200 crank.

7. Quintuplex pump has a crank of ____
a) 60o
b) 72o
c) 120o
d) 1800o

View Answer

Answer: b [Reason:] Quintuplex pump has five single acting cylinders with separate suction and delivery having 72o crank.

8. The number of valves required in rotary pump is
a) 0
b) 1
c) 2
d) 3

View Answer

Answer: a [Reason:] No valves are required in rotary pump and the flow is continuous. Gear, Lobe and Vane pumps are the examples of rotary pump.

9. Consider the following statement regarding Reciprocating pump.
1. High initial cost
2. Requires a small space
3. Less power required
Which of the following is/are incorrect statement?
a) Only 1
b) Only 2
c) Only 3
d) 2, 3

View Answer

Answer: d [Reason:] The reciprocating pump has high initial and maintenance cost, more power required and required large space.

Set 3

1. What is formed when coagulant is added to water?
a) Scum
b) Soap
c) Bubbles
d) Floc

View Answer

Answer: d [Reason:] When coagulant is added to water, then white gelatinous precipitate is formed called as floc.

2. The chemical composition of Alum is
a) Al2 (SO4)3.18H2O
b) Al2 (SO4)2.18H2O
c) Al3 (SO4)2.18H2O
d) Al4 (SO4)3.18H2O

View Answer

Answer: a [Reason:] Alum is the most common and universal coagulant used in water treatment having chemical composition Al2 (SO4) 3.18H2O.

3. The chemical compound which is insoluble in water, formed when alum is added to water is _____
a) Al (OH)3
b) CaSO4
c) CO2
d) Ca (OH)3

View Answer

Answer: a [Reason:] Al2 (SO4)3.18H2O + 3Ca (HCO3)2 = 2Al (OH)3 + 3CaSO4 + 18H2O + CO2 Where Al (OH)3 is insoluble in water.

4. Which gas is released when alum is added to water?
a) Al (OH)3
b) CaSO4
c) CO2
d) Ca (OH)3

View Answer

Answer: c [Reason:] Carbon dioxide gas is released when alum is added to water, which is corrosive to metals.

5. What indicates the permanent hardness when alum is added to water?
a) Al (OH)3
b) CaSO4
c) CO2
d) Ca (OH)3

View Answer

Answer: b [Reason:] The presence of calcium sulfate indicates the permanent hardness in water when alum is added to water.

6. Alum is effective when pH of water is between ____
a) 8-10
b) 6-8
c) 6.5-8.5
d) 7-9

View Answer

Answer: c [Reason:] Alum is effective when pH of water is between 6.5-8.5. Its dose depends on turbidity, color, taste, pH and temperature of water.

7. Why Alum is preferred over other coagulants?
a) It is easy to dewater the sludge formed
b) It imparts corrosiveness to water
c) It reduces taste and odor in addition to turbidity
d) The time required for floc formation is less

View Answer

Answer: c [Reason:] Alum is preferred over other coagulants because it reduces the taste and odor in addition to turbidity and produce lighter flocs that can be broken easily.

8. The chemical composition of Chlorinated Copperas is
a) Fe2 (SO4)3 + FeCl3
b) FeSO4.9H2O
c) FeSO4.18H2O
d) Fe2 (SO4)3

View Answer

Answer: a [Reason:] 6FeSO4.7H2O2 +3Cl2 = 2Fe2(SO4) 3 + 2FeCl3 +7H2O The ferric sulfate and ferric chloride so formed are called as Chlorinated Copperas.

9. Ferric chloride is effective over a pH range of
a) 3.5-6
b) 6.5-8
c) 3.5-6.5
d) 2-5

View Answer

Answer: c [Reason:] Ferric chloride is effective over a pH range of 3.5-6.5 and above 8.5 whereas if Ferric sulfate is used then, it is effective over a pH range of 4-7 and above 9.

10. Why Magnesium carbonate is not commonly preferred as coagulant?
a) It is expensive
b) It does not remove color
c) Formation of sludge
d) The time required for floc formation is less

View Answer

Answer: c [Reason:] When magnesium carbonate and lime are dissolved in water, magnesium hydroxide and calcium carbonate are formed which are soluble in water and sludge is formed in slurry form, so they are not commonly used.

11. Which of the following statement is wrong regarding Iron salt?
a) Iron salt produces less floc than Alum
b) Detention time for sedimentation by using Iron salt as coagulant is less
c) Handling of Iron salt requires some skills
d) Iron removes H2S, taste and odor

View Answer

Answer: a [Reason:] Iron salt produces heavy floc due to which more suspended matter is removed than with alum.

Set 4

1. A Service connection is a connection from the distribution system to the ______
a) Factory
b) School
c) Industry
d) Consumer

View Answer

Answer: d [Reason:] A consumer can be a single house, an apartment or a planned block development. A connection to a single house involve tapping the main and installing a corporation cock.

2. Which of the following is not a component of domestic service connection?
a) Water meter
b) Stopcock
c) Tube settler
d) Gooseneck

View Answer

Answer c: [Reason:] The various components of a domestic service connection are Brass ferrule, Gooseneck, Stopcock, Mains service pipe and Water meter.

3. The length of Goose neck in a domestic service connection is
a) 10cm
b) 20cm
c) 30cm
d) 40cm

View Answer

Answer: d [Reason:] The Goose neck consists of 40-50cm curved piece of pipe which prevents the breaking of the main service pipe.

4. Which device is used to measure quantity of water consumed by the consumer?
a) Water meter
b) Stopcock
c) Tube settler
d) Gooseneck

View Answer

Answer: a [Reason:] Water meter is used to measure quantity of water consumed by the consumer. It is installed in a suitable chamber with cover.

5. Which of the following is incorrect regarding water meter?
a) Should be durable
b) Easy to maintain and repair
c) Should allow backflow of water
d) Should be rugged

View Answer

Answer: c [Reason:] Water meter should prevent the back flow of water passing through it. It should not be liable to clogging.

6. Which device is used to measure velocity of flow for high flows?
a) Water meter
b) Inferential meter
c) Globe valve
d) Gate valve

View Answer

Answer: b [Reason:] Inferential meter measures the velocity of flow across a cross section whose area is known. They are only used for high flows.

7. Which of the following is an example of Inferential meter?
a) Turbine meter
b) Hydrometer
c) Water meter
d) Gate valve

View Answer

Answer: a [Reason:] Turbine and rotary meters are the examples of Inferential meter. It is also called as velocity meter as they measure the velocity of flow.

8. Which device is used to measure velocity for low flows?
a) Water meter
b) Inferential meter
c) Globe valve
d) Displacement meter

View Answer

Answer: d [Reason:] Displacement meter is used to measure velocity for flows. Reciprocating, Rotary, Oscillating and Nutating disc meter are the examples of Displacement meter.

9. Which of the following pipe material has a maximum modulus of elasticity?
a) Concrete
b) Mild steel
c) Cast iron
d) PVC

View Answer

Answer: b [Reason:] Mild steel has the maximum modulus of elasticity with a magnitude of 2.1 *1010. The modulus of elasticity of concrete, cast iron and PVC are 2.8*109, 7.5*109 and 3*108 respectively.

Set 5

1. The depth of an enclosed tank of a slow sand filter lies in the range of ______
a) 1-2m
b) 2.5-4m
c) 2-5m
d) 3-5m

View Answer

Answer: b [Reason:] The depth of an enclosed tank of a slow sand filter lies in the range of 2.5-4m and its surface area lies between 50-1000m2.

2. When the fineness of sand increases
a) The bacterial efficiency increases
b) The rate of filtration increases
c) The rate of filtration first decrease, then increase
d) The bacterial efficiency remains constant

View Answer

Answer: a [Reason:] When the fineness of sand increases, the bacterial efficiency increases, but rate of filtration decreases. Fine sand is preferred when high bacteria and turbidity removal efficiency is desired.

3. The thickness of the base material on which filter media are supported is
a) 10-100cm
b) 20-80cm
c) 30-75cm
d) 10-30cm

View Answer

Answer: c [Reason:] The base material consists of 30-75 cm thick gravel bed which is laid in layers of 15 cm with finer topmost layer and coarser bottom layer.

4. The minimum number of filter beds in the slow sand filter is
a) 1
b) 2
c) 3
d) 3

View Answer

Answer: b [Reason:] The minimum number of filter beds provided in the slow sand filter is 2 where one unit is provided as stand by for an area of 20m2.

5. The area of the filter is 1500. What is the number of beds to be provided?
a) 1
b) 2
c) 3
d) 6

View Answer

Answer: b [Reason:] The area of filter is 1500 which lies between 1201-2000m2. So, the number of beds to be provided is 6.

6. The slow sand filter is able to remove ______ % of bacteria in water.
a) 90
b) 95
c) 98-99
d) 100

View Answer

Answer: c [Reason:] The slow sand filters are highly efficient in the removal of bacteria and can remove around 98-99% of bacteria present in water.

7. State whether the following statement is true or false.
The slow sand filter is efficient in removing turbidity of water.
a) True
b) False

View Answer

Answer: b [Reason:] The slow sand filter is not efficient in removing turbidity of water and is not capable of removing turbidity over 50ppm.

8. The maximum daily demand of a city is 24*105 and the rate of filtration is 100 per litre per hour per m2. What is the area of the filter?
a) 10
b) 100
c) 1000
d) 1500

View Answer

Answer: c [Reason:] Maximum daily demand = 24*105 Rate of filtration = 100 Area of filter=Maximum daily demand/Rate of filtration=24*105/(100*24) =1000m2.

9. The slow sand filter is designed for
a) Maximum daily demand
b) Maximum yearly demand
c) Average daily demand
d) Maximum weekly demand

View Answer

Answer: a [Reason:] The slow sand filter is designed for maximum daily demand, which is 1.8 times the average daily demand.

10. What is the frequency of cleaning of a slow sand filter?
a) 1 week
b) 1-3 months
c) 2-3 days
d) 2-3 weeks

View Answer

Answer: b [Reason:] The slow sand filter requires cleaning, depending upon the impurities present in water and normally it is done after 1-3 months.

11. What is the maximum filter head up to which slow sand filters are worked upon?
a) 25cm
b) 50cm
c) 75cm
d) 100cm

View Answer

Answer: c [Reason:] Initially the filter head is only 10-15cm but it increases as suspended matter is arrested. When the filtration head reaches the maximum permissible value of 75cm, the filter requires cleaning.