IBX - CPI Sec. 10 to 12 Flashcards
IndiaBIX - Chemical Process (Sections 10 to 12) (150 cards)
1
Q
A unit operation is exemplified by the process of
reduction
desorption
nitration
combustion
A
desorption
2
Q
The major constituents of glass are
lime, clay and soda ash
sand, lime and soda ash
silica, alumina and clay
silica, alumina and soda ash
A
sand, lime and soda ash
3
Q
Margarine is a/an
fat
explosive
plasticiser
rocket propellant
A
fat
4
Q
Oils and fats are converted to soap in a process called
hydrogenation
esterification
saponification
none of these
A
saponification
5
Q
Glycerine can be obtained from
fat
naphthalene
cumene
sucrose
A
fat
6
Q
Blue vitriol is chemically
copper sulphate
ferrous sulphate
copper nitrate
aluminium sulphate
A
copper sulphate
7
Q
Trinitro-toluene (TNT) is
used in glycerine manufacture.
an explosive.
used in dye manufacture.
none of these.
A
an explosive.
8
Q
Thorium is mainly used
for the manufacture of gas mantles.
as a fissile fuel in a nuclear reactor.
in the manufacture of hydrogen bomb.
in the treatment of cancer.
A
for the manufacture of gas mantles.
9
Q
During the absorption of HCl gas in water (to produce liquid HCl), the gas is kept above dew point to
increase the rate of absorption.
avoid corrosion.
reduce the cooling water circulation rate.
none of these.
A
avoid corrosion.
10
Q
Good quality of edible salt is obtained from brine by the process of
solar evaporation
vacuum evaporation
freeze drying
electrolysis
A
vacuum evaporation
11
Q
Electric bulbs are made of __________ glass.
jena
flint
crookes
pyrex
A
flint
12
Q
Which of the following is used as a binding material in soap to improve soap texture?
Rosin
Borax
Benzyl acetate
Sodium carbonate
A
Borax
13
Q
An alkali metal salt of palmitic acid is known as
soap
metallic soap
detergent
alkaloid
A
metallic soap
14
Q
Washing soda is chemically represented by
Na2CO3
Na2CO3⋅H2O
Na2CO3⋅10H2O
NaHCO3
A
Na2CO3⋅10H2O
15
Q
Magnesium and calcium __________ cause temporary hardness of water.
carbonates
bicarbonates
phosphates
sulphates
A
bicarbonates
16
Q
Which form of sulphur is the most stable at room temperature ?
Plastic
Monoclinic
Rhombic
Flowers of sulphur
A
Rhombic
17
Q
Vegetable oils and fats basically differ in their
density ranges
physical state
chemical composition
chemical properties
A
physical state
18
Q
Average sulphur content in Indian pyrites is about __________ percent.
15
35
55
70
A
35
19
Q
Oil is a/an
mixture of glycerides.
mixture of glycerides of fatty acids.
solid at normal temperature.
ester of alcohols other than glycerine.
A
mixture of glycerides of fatty acids.
20
Q
Which of the following is a constituent of coffee?
Caffeine
Nicotine
Calgon
Lignin
A
Caffeine
21
Q
Which of the following is the main constituent of the mother liquor produced in salt industry?
Quick lime
Glauber’s salt
Salt petre
Bromine
A
Bromine
22
Q
Silicon carbide is a/an
adhesive
abrasive
type of glass
brittle material
A
abrasive
23
Q
Oxygen is produced by fractionation of air using __________ process.
Linde’s
Claude’s
either (a) or (b)
none of these
A
either (a) or (b)
24
Q
Trinitrotoluene (TNT), an explosive, is made by the nitration of
nitrobenzene
toluene
nitrotoluene
benzene
A
toluene
25
Which of the following is used as a coagulant in treating turbid water?
Chlorine
Ferric sulphate
Calcium sulphate
Activated carbon
Ferric sulphate
26
Carborundum consists mainly of
bauxite
silicon carbide
boron carbide
calcium carbide
silicon carbide
27
Wax is a
mixture of glycerides.
mixture of esters of polyhydric alcohols excepting glycerine.
liquid at room temperature.
mixture of glycerides of fatty acids.
mixture of esters of polyhydric alcohols excepting glycerine.
28
Catalyst used in the hydrogenation of oil is
nickel
platinum
iron
alumina
nickel
29
Viscose rayon is
cellulose nitrate.
regenerated cellulose nitrate.
regenerated cellulose acetate.
none of these.
none of these.
30
Triple superphosphate is manufactured by reacting
phosphate rock with phosphoric acid.
phosphate rock with sulphuric acid.
phosphate rock with nitric acid.
ammonium phosphate with phosphoric acid.
phosphate rock with phosphoric acid.
31
Use of hydrated lime in water treatment
before filtration, reduces the bacterial load on filters.
after filtration, combats the corrosive-ness of water due to the presence of O2 & CO2.
is to adjust the pH value.
all (a), (b) and (c).
all (a), (b) and (c).
32
Higher vicosity index of a lubricating oil denotes
less changes in fluidity of oil with temperature.
substantially high change in fluidity of oil with temperature.
its unsuitability under varying temperature conditions .
none of these.
less changes in fluidity of oil with temperature.
33
Le-Blanc process is a primitive process for the manufacture of
caustic soda
soda ash
bromine from sea water
hydrochloric acid
soda ash
34
How much temperature is maintained during quicklime manufacture in the calcination zone of the vertical shaft kiln?
500°C
750°C
1000°C
1500°C
1000°C
35
Cement setting under water employs a/an __________ process.
hydration
decomposition
oxidation
reduction
hydration
36
__________ are added in lacquers to remove film brittleness and to improve adhereness.
Film forming materials
Plasticisers
Diluents
Solvents
Plasticisers
37
Washing of coal is done to
remove the inherent impurities.
remove the adhering impurities.
reduce the ash content.
both(b) and (c).
both(b) and (c).
38
Systemic insecticides
are absorbed throughout the plant.
kill insects following external bodily contact.
are stomach poisons.
emit poisonous vapour.
are absorbed throughout the plant.
39
Dry ice (solidified CO2) is used for the
storage & shipment of frozen foods and ice-creams.
liquefaction of permanent gases.
liquefaction of natural gas.
none of these.
storage & shipment of frozen foods and ice-creams.
40
In nylon-66, the first and second numbers (i.e., 6) respectively designate the number of carbon atoms present in the
diamine and the ring.
dibasic acid and the ring.
diamine and the dibasic acid.
none of these.
diamine and the dibasic acid.
41
Chemical formula of BHC, which is an insecticide is
C6H6Cl6
C6Cl6
C6H5Cl
C6H4Cl2
C6H6Cl6
42
A bio-catalyst produced by living cells which acts independent of the cell is called a/an
substrate
enzyme
nutrient
none of these
enzyme
43
Pick out the wrong statement.
DDT is manufactured by the condensation of chlorobenzene with chloral at 30°C in presence of oleum, which is a highly exothermic reaction.
Chloral is obtained by the chlorination of ethyl alcohol.
Insecticides acting on the insects through the respiratory system are called fumigants.
Benzene hexachloride is not a contact insecticide.
Benzene hexachloride is not a contact insecticide.
44
The product obtained on mixing calcium oxide with water is called
quicklime
slaked lime
milk of lime
none of these
slaked lime
45
The major constituent of black liquor generated during paper manufacture is sodium
sulphate
carbonate
hydroxide
bi-carbonate
carbonate
46
Plaster of Paris is
CaSO4.H2O
used for setting of broken bones
both (a) and (b)
same as gypsum
both (a) and (b)
47
Exothermic neutralisation reaction between caustic soda and dodecylbenzene sulphonic acid produces sodium dodecylbenzene sulphate, which is a/an
explosive
soap
detergent
analgesic drug
detergent
48
Conversion of SO2 to SO3 in Monsanto 4-pass converter is about __________ percent.
80
90
98
100
98
49
Coke oven gas consists mainly of
H2, & CH4
CO, & CO2
H2, & CO
CH4, & CO
H2, & CH4
50
Chemical name of 'alum' is
barium sulphate.
aluminium sulphate.
aluminium chloride.
calcium sulphate.
aluminium sulphate.
51
Lithopone is
explosive
white lead
filter aid
ZnS (white pigment)
ZnS (white pigment)
52
What products do we get on electrolysis of saturated brine using steel cathode and graphite anode in an electrolytic cell?
Cl2 & Na
Cl2 & H2
O2 & H2
Cl2, H2 & NaOH solution.
Cl2, H2 & NaOH solution.
53
__________ acid is the main constituent of cotton seed oil.
Acetic
Linoleic
Palmitic
Oleic
Linoleic
54
Chemical formula of 'salt cake' is
Na2SO4
CaSO4
MgSO4
BaSO4
Na2SO4
55
Temperature during hydrogenation of oil should not be more than 200°C, otherwise it will result in
pyrolysis of oil.
sintering of porous catalyst.
hydrogen embrittlement.
all (a), (b) and (c).
all (a), (b) and (c).
56
Nicotine is
a volatile alkaloid.
obtained by treating by-products of the tobacco processing industry.
both (a) and (b).
neither (a) nor (b).
both (a) and (b).
57
Separation of fresh water from sea water can be done by the __________ operation.
osmosis
reverse osmosis
absorption
adsorption
reverse osmosis
58
Na2CO3⋅10H2O is called
washing soda
soda ash
slaked lime
quicklime
washing soda
59
Reaction of an alcohol with organic acid is called the __________ reaction.
saponification
esterification
neutralisation
acidification
esterification
60
Ethanol amine is produced using ammonia and
ethyl benzene
ethylene oxide
ethanol
ethane
ethylene oxide
61
__________ acid is an unsaturated fatty acid.
Palmitic
Oleic
Stearic
Oxalic
Oleic
62
CO & H2 are the constituents of
producer gas
water gas
coke oven gas
all (a), (b) and (c)
all (a), (b) and (c)
63
Economics of 'Solvay Process' depends upon the efficiency of
carbonating tower
ammonia recovery
ammonia recovery and size of the plant
ammoniation of salt solution
ammonia recovery and size of the plant
64
__________ is a thermosetting plastic.
Polyvinyl chloride
Polythene
Bakelite
Teflon
Bakelite
65
Na2CO3 is called
washing soda
soda ash
plaster of paris
calcite
soda ash
66
Flux addition during smelting of ore is done to
remove impurities/gangue.
enhance rate of reaction.
accelerate reduction of ore.
separate slag from metal.
remove impurities/gangue.
67
Hydrazine is used in water treatment for the removal of
colloidal impurities
dissolved oxygen
turbidity
chlorinous taste
dissolved oxygen
68
Direct conversion of chemical energy into electrical energy is done in a
magnetohydrodynamic (MHD) generator.
fuel cell.
fast breeder reactor.
none of these.
fuel cell.
69
Which of the following is not produced commercially from sea water ?
Magnesium & potassium compounds
Common salt
Bromine
Iodine
Iodine
70
Pick out the wrong statement.
Dry process is used for the manufacture of cement, when the raw material is blast furnace slag.
Portland cement is made employing wet process.
Gypsum is added to portland cement to lengthen its setting time.
none of these.
none of these.
71
Nylon-6 as compared to Nylon-66 is having higher
hardness
abrasion/resistance
melting point
none of these
none of these
72
Digestion of wood-base materials (for manufacture of pulp) is done to
remove lignin.
produce long fibres.
prevent deterioration on storage.
none of these.
remove lignin.
73
Soap cannot be used with hard water, because
hard water contains sulphate.
they form insoluble calcium soaps which precipitate.
they attract back the removed dirt.
none of these.
they form insoluble calcium soaps which precipitate.
74
Which of the following is not an antibiotic?
Penicillin
Streptomycin
Tetracyclin
Quinine
Quinine
75
The most reactive allotropic form of phosphorus is __________ phosphorus.
red
yellow
violet
black
yellow
76
Plasticisers are added to synthetic plastics to
impart flexibility.
improve workability during fabrication.
develop new improved properties not present in the original resins.
all (a), (b) and (c).
all (a), (b) and (c).
77
Rosin soap is added during paper manufacture to
impart adhesive properties.
improve opacity.
impart resistance to penetration by liquids.
none of these.
impart resistance to penetration by liquids.
78
Hydrogen gas is not produced commercially (for nitrogeneous fertiliser manufacture) by
iron-steam reaction.
electrolysis of water.
steam reforming of naphtha.
its cryogenic separation from coke oven gas.
iron-steam reaction.
79
Carboxymethyl cellulose (CMC) is added in detergents to
prevent redeposition of soil on cleaned surface.
act as optical brightening agent.
inhibit corrosion in washing machines made of aluminium,
none of these.
prevent redeposition of soil on cleaned surface.
80
Synthesis gas is a mixture of
CO and H2
N2 and H2
H2, CH4 and CO
CO2 and H2
CO and H2
81
Which of the following impurities in feed water for high pressure boiler is the most detrimental?
Silica
Dissolved oxygen
Suspended salt
Dissolved salt
Silica
82
Which glass is usually used in optical work?
Lead glass
High silica (borosilicate) glass
Photo-sensitive glass
Fibre glass
Lead glass
83
Fourdrinier machine is used in the manufacture of
sugar
paper
alcohol from molasses
phenol formaldehyde
paper
84
The most popular and common detergent i.e., alkyl benzene sulfonate (ABS) is a/an __________ detergent.
cationic
anionic
amphoteric
semi polar
anionic
85
Reaction of calcium carbide with water produces a gas, which is used
as an illuminant.
for metal cutting/welding.
both (a) & (b).
neither (a) nor (b).
both (a) & (b).
86
Salt is the basic raw material for the manufacture of
cement
glass
potteries
caustic soda
caustic soda
87
Pick out the wrong statement.
Low intensity explosives are also called propellants, whereas high intensity explosive are called detonators.
Gun powder comprises of 75% salt petre, 15% charcoal and 10% sulphur.
Lead azide is a popular military explosive.
TNT is a hygroscopic explosive having very high melting point and is non-toxic to human being.
TNT is a hygroscopic explosive having very high melting point and is non-toxic to human being.
88
Hydrazine (N2H4) is used mainly as a/an
explosive
rocket fuel
detergents additive
none of these
rocket fuel
89
Hydrocynic acid (HCN) is used as an insecticide for
controlling timber degradation by ants
controlling poultry lice
potato beetle
citrus fruits
citrus fruits
90
Molecular weight of plastics ranges from
5000 to 10000
20000 to 250000
500 to 5000
106 to l09
20000 to 250000
91
Acrylonitrile is mainly used in the __________ industry.
polymer
printing
dyeing
photographic
dyeing
92
The enzyme which converts starch into the dissacharides maltose is
diastase
maltase
yeast
none of these
diastase
93
Pick out the false statement pertaining to water treatment.
Aeration of water is effective in CO2 removal.
The zeolite water softening process reduces the hardness of water by not more than 50%.
Sodium sulphate or sodium carbonate do not cause hardness in water.
Water with pH value less than 7, is acidic.
The zeolite water softening process reduces the hardness of water by not more than 50%.
94
Presence of H2S in raw water (to be chlorinated) results in the
reduced softening capacity of zeolite.
increased dosage of chlorine to provide a disinfecting residual in the water.
easy removal of its hardness.
none of these.
increased dosage of chlorine to provide a disinfecting residual in the water.
95
Contact process of sulphuric acid manufacture
yields acid of higher concentration than chamber process.
yields acids of lower concentration than chamber process.
is obsolete.
eliminates absorber.
yields acid of higher concentration than chamber process.
96
Fat dispersed in water is exemplified by
colloids
gel
butter
emulsion
butter
97
Maleic anhydride is produced by catalytic oxidation of
toluene
ethyl alcohol
naphthalene
benzene
benzene
98
Catalyst used in the oxidation of benzene to produce maleic anhydride is
V2O5
Pt
Ni
Cr
V2O5
99
Widely used method for the conditioning of boiler feed water is the
cold lime process
coagulation
hot-lime soda process
sequestration
hot-lime soda process
100
Blue colour is imparted to glass by the addition of
FeSO4
PbO
CaO
NaOH
CaO
101
In the manufacture of viscose rayon, the raw material used industrially is
recalyptious wood
bamboo
bagasse
fine teak wood
fine teak wood
102
Bordeaux mixture is a/an
fertiliser
inorganic fungicide
insecticide
explosive
inorganic fungicide
103
Silicone is a/an
thermoplastic
inorganic polymer
monomer
none of these
inorganic polymer
104
Nickel is not used as a catalyst in the __________ reaction.
shift conversion
oil hydrogenation
steaming reforming of naphtha
ammonia cracking/dissociation
shift conversion
105
Roasting of metallurgical ores is done mainly to
dehydrate it.
sinter the ore.
remove CO2 & H2O.
remove arsenic & sulphur.
remove arsenic & sulphur.
106
Molasses is the starting material for the production of
alcohol
essential oil
fatty acids
massecuite
alcohol
107
BHC (Benzene hexachloride) is made by the chlorination of benzene
which is an addition reaction.
which is a substitution reaction.
in absolute dark.
in presence of sunlight.
which is an addition reaction.
108
Diaphragm electrolytic cell as compared to mercury electrolytic cell
produces 70% NaOH solution.
requires less specific power consumption for the production of chlorine.
requires lesser investment for similar capacity.
all (a), (b) and (c).
requires lesser investment for similar capacity.
109
Calcareous & argillaceous materials are used in the manufacture of
lead
cement
carbon disulphide
none of these
cement
110
Pick out the wrong statement.
Azoic dyes are mostly applied on cotton fabrics.
Basic dyes (e.g. amino derivatives) are applied mostly to paper.
Mordant dyes are applied mainly to wools.
none of these.
none of these.
111
Commercial production of calcium carbide requires limestone and __________ as raw materials.
coke
sand
soda ash
fuel oil
coke
112
Which one of the following is not likely to be a constituent of vegetable oils?
Citric acid
Oleic acid
Stearic acid
Glycerol
Citric acid
113
Nitroglycerene absorbed in wood flour, sodium nitrate or ammonium nitrate is commercially used as a controlled explosive called dynamite. The raw material used for its manufacture are glycerene, nitric acid and
sulphuric acid
phosphoric acid
hydrochloric acid
hydroflouric acid
sulphuric acid
114
The process involved in converting rubber into a thin sheet or coating it on fabric is called
extrusion
mastication
calendering
valcanisation
calendering
115
Detergent is produced by the sulphonation of dodecyl benzene, which is an __________ reaction.
endothermic
exothermic
irreversible
both (b) and (c)
both (b) and (c)
116
Air used in aerobic fermentation must be sterilized, otherwise the
recovery of product will be difficult.
contamination of pure culture would result.
uniformity of product cannot be achieved.
none of these.
contamination of pure culture would result.
117
Alkylbenzene sulfonate (ABS) is a
detergent
rubber
pesticide
polyester
detergent
118
High temperature carbonisation of coal produces
inferior coke compared to low temperature carbonisation.
less of gases compared to liquid products.
larger quantity of tar compared to low temperature carbonisation.
none of these.
none of these.
119
Alcohol content in freshly prepared natural and fortified wine may be respectively around __________ percent.
7-14 and 14-30
7-14 and 40-50
14 - 30 and 40-50
10 - 20 and 40 - 50
7-14 and 14-30
120
Setting of plaster of paris is accompanied with
hydration
dehydration
hydrolysis
loss of CO2
hydration
121
Process conditions in fermentator used for production of penicillin is
25°C, 2 atm.
50°C, 10 atm.
30°C, 200 mm Hg (absolute).
90°C, 45 atm.
25°C, 2 atm.
122
Platinum is a versatile catalyst for many processes in chemical industries. It is highly prone to be poisoned by the presence of
carbon
arsenic
lead
sulphur
arsenic
123
Sodium chloride content in sea water is about __________ gms/litre.
2
10
25
50
25
124
Fluorescent dyes are added in detergents to
act as fabric brightener (by converting ultraviolet light to visible light) thereby improving the whiteness appearance of white fabrics.
attain distinctiveness from other brands.
act as tarnish inhibitor for metals like German silver.
none of these
act as fabric brightener (by converting ultraviolet light to visible light) thereby improving the whiteness appearance of white fabrics.
125
High magnesia lime is added to hot sugar cane juice (during the manufacture of sugar) to
flocculate the impurities.
facilitate fast filtration.
both (a) and (b).
neither (a) nor (b).
both (a) and (b).
126
Polyvinyl chloride (PVC) is
a thermosetting material.
a condensation polymerisation product.
made by employing emulsion polymerisation.
none of these.
made by employing emulsion polymerisation.
127
Bleaching of paper pulp is done with
activated clay
bromine
chlorine or chlorine dioxide
magnesium sulphite
chlorine or chlorine dioxide
128
Pick out the wrong statement.
Kraft method of pulp manufacture can process all types of fibrous raw materials.
Digestion time for bagasse is less than that for wood base materials.
Both temperature and pressure in the digestor is less in case of the sulphite method as compared to that in the sulphate method.
none of these.
none of these.
129
Isopropyl benzene produced by alkylation of benzene with propylene is known as
neoprene
cumene
gelatin
mercaptans
cumene
130
Consider the production of ammonia from methene and air as raw materials. The catalyst used are: (i) __________ for steam reforming of methane and (ii) __________ for ammonia synthesis.
i - Ni/Al2O3; ii - Cu - ZnO/Al2O3
i - Fe/Al2O3; ii - Cu - ZnO/Al2O3
i - Ni/Al2O3; ii - Fe/Al2O3
i - Fe/Al2O3; ii - Ni/Al2O3
i - Ni/Al2O3; ii - Fe/Al2O3
131
For the hydrogenation of oils __________ (A) __________ is commonly used as catalyst and __________ (B) __________ is a catalyst poison.
(A) platinum (B) sulphur
(A) palladium (B) oxygen
(A) nickel (B) sulphur
(A) nickel (B) oxygen
(A) nickel (B) sulphur
132
Main constituents of natural rubber is
polystyrene
polyisoprene
polybutadiene
polychloroprene
polyisoprene
133
Highly porous refractory bricks are
less susceptible to chemical attack by molten fluxes and gases etc.
very strong.
having very high thermal conductivity.
none of these.
none of these.
134
Fumigant insecticides
kill insects, when they eat it.
emit poisonous vapour.
are absorbed throughout the plant.
none of these.
emit poisonous vapour.
135
Which of the following is an endothermic reaction?
Absorption of SO3 in 98% H2SO4.
C + H2O = CO + H2.
Thermal dissociation of iron pyrites.
Both (b) and (c).
Both (b) and (c).
136
Fermentator temperature during production of alcohol from molasses is around __________ °C.
5
30
150
300
30
137
Which of the following coals has the highest calorific value?
Lignite
Sub-bituminous
Anthracite
Peat
Anthracite
138
Which of the following is not an abrasive material?
Bakelite
Pumice
Corundum
Carborundum
Bakelite
139
Pick out the wrong statement.
Hard glass which is used for making laboratory glass wares is a mixture of sodium borosilicate and aluminium borosilicate.
Glass is decolorised during its manufac-ture by adding antimony oxide, mangnese dioxide or arsenic oxide.
Ordinary glass is represented chemically by Na2O . CaO . 6SiO2.
Red color is imparted to glass by addition of arsenic oxide.
Red color is imparted to glass by addition of arsenic oxide.
140
Finely ground calcium aluminate & silicate is a/an
cermet
cement
abrasive
explosive
cement
141
Cooking liquor in case of sulphite process is
sodium sulphite and sodium bisulphite.
magnesium sulphite and free SO2 in acid medium.
magnesium sulphate and magnessium bicarbonate.
none of these.
sodium sulphite and sodium bisulphite.
142
90% of the caprolactum is converted to nylon-6 on its condensation polymerisation in the reactor maintained at __________ °C.
<0
10-30
250-280
500-600
10-30
143
Vegetable oils contain large quantity of glycerides of unsaturated acids. When the vegetable oils contain high amount of saturated fatty acids, it is termed as __________ oil.
drying
semi-drying
non-drying
none of these
non-drying
144
Fats as compared to oils have
more unsaturated glycerides of fatty acids.
less unsaturated glycerides of fatty acids.
much higher reactivity to oxygen.
lower melting point.
less unsaturated glycerides of fatty acids.
145
Thermal pyrolysis of ethylene dichloride produces
trichloroethylene
vinyl chloride
ethanol amine
ethylene oxide
vinyl chloride
146
The main component of pyrex glass is
zinc
lead
boron
celenium
lead
147
Alum [Al2(SO4)3] is used as a coagulant in water treatment to remove
colour
turbidity
bacteria
all (a), (b) and (c)
all (a), (b) and (c)
148
__________ is an ore concentrating metallurgical process involving a chemical change.
Electromagnetic separation
Froth floatation
Roasting
none of these
Roasting
149
Basic oxide is absent in __________ glass.
flint
pyrex
quartz
all (a), (b) & (c)
quartz
150
Graphite is a/an
electrical insulator.
allotrope of carbon.
moderator used in nuclear reactor.
both (b) and (c).
both (b) and (c).
