Deck 6: Compounds, Fluoridation, and Oxidation Resistance

Question 1

Which of the following is the pure compound?

A)Sodium fluoride
B)Sodium silico fluoride
C)Hydrofluosilicic acid
D)Sodium fluro carbonate

Answer 1

Sodium fluoride

Question 2

As far as safer handling is considered, which of the following is used for fluoridation?

A)Sodium fluoride
B)Sodium silico fluoride
C)Hydrofluosilicic acid
D)Sodium fluro carbonate

Answer 2

Hydrofluosilicic acid

Question 3

What happens when water contains 8-20 ppm of fluoride concentration?

A)Blue baby disease
B)Crippling fluorosis
C)Dental fluorosis
D)Mottling of teeth

Answer 3

Crippling fluorosis

Question 4

The process of reducing the fluoride content from water is called _____

A)Chlorination
B)Fluoridation
C)Defluoridation
D)Flocculation

Question 5

Which of the following is not used for defluoridation?

A)Calcium phosphate
B)Copper sulfate
C)Alum
D)Bone charcoal

Question 6

At which temperature, the bone is calcinated during defluoridation with calcium phosphate?

A)100-200^oC
B)200-300^oC
C)400-600^oC
D)500-800^oC

Question 7

One cubic metre of bone can treat how much quantity of water containing 3.5 ppm of fluoride?

A)10m³
B)100m³
C)1000m³
D)10000m³

Question 8

Which material is used in contact filters for the removal of fluorides?

A)Calcium phosphate
B)Copper sulfate
C)Synthetic tri-calcium phosphate
D)Bone charcoal

Question 9

Which material is used for removing fluorides from hard water containing 3ppm of fluorides?

A)Lime
B)Copper sulfate
C)Synthetic tri-calcium phosphate
D)Bone charcoal

Question 10

Fluorex is a special mixture of ____________

A)Di-calcium phosphate and carbon
B)Tri-calcium phosphate and hydroxyapatite
C)Di-calcium phosphate and phosphoric acid
D)Tri-calcium phosphate and carbon

Question 11

Which of these materials is not added to iron for improving its oxidation resistance?

A)Nickel
B)Chromium
C)Aluminum
D)Silicon

Question 12

How much chromium is required to provide oxidation resistance for use over 1000^oC?

A)1%
B)6%
C)12%
D)17%

Question 13

Molybdenum with hydrogen can be used up to ________

A)1000^oC
B)1500^oC
C)2000^oC
D)4000^oC

Question 14

% chromium mixed with ______ can be used up to 1100^oC.

A)Nickel
B)Chromium
C)Aluminum
D)Silicon

Question 15

Which of these metals does not require alloying for oxidation resistance?

A)Iron
B)Copper
C)Aluminum
D)Molybdenum

Question 16

_________ is used to prevent duralumin from corrosion.

A)Iron
B)Kynal
C)Titanium
D)Alclad

Question 17

Galvanized ion is made by dipping low carbon steel in molten zinc at ________

A)100^oC
B)150^oC
C)200^oC
D)450^oC

Question 18

Which of these is not a way to prevent intergranular corrosion?

A)Reduction of carbon level
B)Quenching
C)Addition of carbide forming elements
D)Reduction of alloying elements

Question 19

Dezincification of brass is prevented by addition of ________

A)Nickel
B)Zinc
C)Arsenic
D)Tungsten

Question 20

Season-cracking can be prevented by cold-working of brass at _________

A)15oC
B)100^oC
C)300^oC
D)550^oC

Question 21

How can caustic embrittlement be avoided?

A)Addition of nickel
B)Increasing potential
C)Decreasing carbon
D)Adding tannins

Question 22

A grit chamber is usually installed ______ primary sedimentation tanks.

A)Before
B)After
C)In between
D)In

Question 23

At what velocity will the particles settle down?

A)0.5 m/s
B)0.3 m/s
C)0.1 m/s
D)0.25 m/s

Question 24

Grit chambers are constructed to prevent their accumulation in _______

A)Sedimentation tank
B)Sludge digesters
C)Coagulation tank
D)Sand filter

Question 25

What is the cleaning period for manual grit chambers?

A)3 days
B)5 days
C)48 hours
D)1 week