The critical mass of a fissionable material can be reduced by (A) Heating it (B) Cooling it (C) Surrounding it by neutron reflecting material (D) Surrounding it by neutron absorbing material

The critical mass of a fissionable material can be reduced by
(A) Heating it
(B) Cooling it
(C) Surrounding it by neutron reflecting material
(D) Surrounding it by neutron absorbing material
by

1 Answer

Answer :

(C) Surrounding it by neutron reflecting material
by

Related questions

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Description : Neutrons are slowed down in a nuclear reactor by – (1) Fissionable Material (2) Moderator (3) Control rods (4) Cooling system

Last Answer : (2) Moderator Explanation: In thermal nuclear reactors, the coolant acts as a moderator that must slow down the neutrons before they can be efficiently absorbed by the fuel. It allows neutrons to slow down to energies where they can easily cause a nucleus to fission.

Neutrons are slowed down in a nuclear reactor by (1) Fissionable material (2) Moderator (3) Control rods (4) Cooling system

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Last Answer : Moderator

In a breeder reactor, new fuel is formed as non-fuel uranium-238 absorbs a neutron and ultimately becomes which of the following fissionable atoms: w) uranium-235 x) plutonium-239 y) uranium-239 z) neptunium-239

Description : In a breeder reactor, new fuel is formed as non-fuel uranium-238 absorbs a neutron and ultimately becomes which of the following fissionable atoms: w) uranium-235 x) plutonium-239 y) uranium-239 z) neptunium-239

Last Answer : ANSWER: X -- PLUTONIUM-239

Ozone layer in the outer atmosphere helps us in – (1) reflecting radio waves and makes radio communication possible (2) regulating he temperature of atmosphere (3) absorbing cosmic ray particles (4) absorbing U-V radiations

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Last Answer : (4) absorbing U-V radiations Explanation: The ozone layer is a layer in Earth's atmosphere containing relatively high concentrations of ozone (03) which absorbs 97- 99% of the Sun's medium-frequency ultraviolet light.

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A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case, (A) The cooling rate will be the same for the two spheres and hence the two spheres will have equal temperatures at any instant (B) Both the spheres will emit equal amount of radiation per unit time in the beginning (C) Both will absorb equal amount of radiation from the surrounding in the beginning (D) Both (B) & (C)

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Last Answer : (A) 0.71

Heat transfer takes place through a liquid medium surrounding the submerged material under heating, in case of a/an (A) Blast furnace (B) Steam boiler (C) Salt bath furnace (D) Annealing furnace

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Last Answer : (C) Salt bath furnace

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Last Answer : Option C

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Last Answer : (A) Venting off (after burning) the excess inflammable/toxic gases at high pressure

Which reactor produces more fissionable material than it consumes ?

Description : Which reactor produces more fissionable material than it consumes ?

Last Answer : Breeder reactor.

In a nuclear power reactor, fission produces heat which is used to produce electricity. A reactor producing more fissionable material than it consumes is known as what kind of reactor?

Description : In a nuclear power reactor, fission produces heat which is used to produce electricity. A reactor producing more fissionable material than it consumes is known as what kind of reactor? 

Last Answer : ANSWER: BREEDER REACTOR 

Graphite is used in nuclear reactors for- (1) reducing the speed of fast neutrons (2) cooling the reactor (3) absorbing neutrons (4) None of the above

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67 The chemical used in breather for transformer should have the quality of A. Ionizing air B. Absorbing moisture C. Cleansing the transformer oil D. Cooling the transformer oil

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Last Answer : B. Absorbing moisture

Of the following, which non-fissioning element is used in the cooling water of nuclear power plants to help control the rate of the fission reaction by absorbing neutrons: w) zirconium x) boron y) krypton z) cesium

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Last Answer : ANSWER: X -- BORON

The Greenhouse Effect is caused primarily by which of the following processes? w) blocking incoming short wave solar energy x) absorbing incoming short wave solar energy y) heating of the Earth's stratosphere z) absorbing outgoing long wave radiation from the Earth

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Last Answer : ANSWER: Z -- ABSORBING OUTGOING LONG WAVE RADIATION FROM THE EARTH 

If two gases have same reduced temperature and reduced pressure, then they will have the same (A) Volume (B) Mass (C) Critical temperature (D) None of these

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The term "approach" in a cooling tower refers to the difference in the temperature of the (A) Cold water leaving the tower and the wet bulb temperature of the surrounding air (B) Hot water entering the tower and the wet bulb temperature of the surrounding air (C) Hot water entering and the cooled water leaving the cooling tower (D) None of these

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Critical energy should be __________ the neutron binding energy of the atom in order to initiate a nuclear fission. (A) Equal to (B) Less than (C) More than (D) Either more or less

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Last Answer : (C) More than

For absorbing a sparingly soluble gas in a liquid (A) Gas side mass transfer co-efficient should be increased (B) Liquid side mass transfer co-efficient should be increased (C) Liquid side mass transfer co-efficient should be decreased (D) Mass transfer co-efficient must be kept constant

Description : For absorbing a sparingly soluble gas in a liquid (A) Gas side mass transfer co-efficient should be increased (B) Liquid side mass transfer co-efficient should be increased (C) Liquid side mass transfer co-efficient should be decreased (D) Mass transfer co-efficient must be kept constant

Last Answer : (B) Liquid side mass transfer co-efficient should be increased

Supercharging is the process of a. supplying the engine with air at a density greater than the density of the surrounding atmosphere b. providing forced cooling air c. injecting excess fuel d. raising the exhaust pressure

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Last Answer : ANSWER a. supplying the engine with air at a density greater than the density of the surrounding atmosphere

Who discovered that atoms are fissionable ?

Description : Who discovered that atoms are fissionable ?

Last Answer : : Atomic fiction is discovered by Ottohan and Stressman

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Last Answer : ANSWER: Y -- NEUTRONS MODERATED TO RELATIVELY LOW ENERGIES.

There are a multitude of various dressings available. Which of the following statement(s) is/are true concerning options for surgical dressings? a. Hydrocolloids, such as karaya compounds, offer the primary advantage of increased absorptive ability b. Films, such as Op-site, provide a water impermeable environment to achieve a dry wound c. Impregnates are fine gauze impregnated with a variety of substances such as antibiotics or moisturizing agents that adhere tightly to the wound and do not require a secondary dressing d. Absorptive powders and paste are highly useful in debriding necrotic and fibrous material from wounds and absorbing wound serum

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In a nuclear reactor the material use for absorbing neutrons is – (1) zinc (2) radium (3) lead (4) cadmium

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Which is best used as a sound absorbing material in partition walls? (1) Stone chips (2) Steel (3) Glass – wool (4) Glass pieces

Description : Which is best used as a sound absorbing material in partition walls? (1) Stone chips (2) Steel (3) Glass – wool (4) Glass pieces

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Which is best used as a sound absorbing material in partition walls? (1) Stone chips (2) Steel (3) Glass - wool (4) Glass pieces

Description : Which is best used as a sound absorbing material in partition walls? (1) Stone chips (2) Steel (3) Glass - wool (4) Glass pieces

Last Answer : (3) Glass - wool Explanation: Materials that do not transfer mechanical energy well. These tend to be soft, flexible, low density, and with high surface area to linear area ratios.

In a nuclear reactor the material use for absorbing neutrons is (1) zinc (2) radium (3) lead (4) cadmium

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Last Answer : cadmium

Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for (A) Cube (B) Cylinder (C) Sphere (D) Equal for all the three

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Last Answer : (A) Cube

Critical mass" is the minimum mass of nuclear fissile material required for the (A) Sustainment of chain reaction (B) Power generation on commercial scale (C) Economic power generation (D) None of these

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Last Answer : (A) Sustainment of chain reaction

Mass of a positron is same as that of a/an (A) Electron (B) α-particle (C) Proton (D) Neutron

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Last Answer : (A) Electron

The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron? (A) 159 (B) 1837 (C) 2537 (D) 10000

Description : The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron? (A) 159 (B) 1837 (C) 2537 (D) 10000

Last Answer : (B) 1837

The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron? (A) 159 (B) 1837 (C) 2537 (D) 10000

Description : The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron? (A) 159 (B) 1837 (C) 2537 (D) 10000

Last Answer : Option C

JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by (A) Nsh = 2 (B) Nst = 2 (C) Nsc = 2 (D) None of these

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Last Answer : (A) Nsh = 2

A fertile material is the one, which can be (A) Converted into fissile material on absorption of neutron (B) Fissioned by slow (thermal) neutrons (C) Fissioned by fast neutrons

Description : A fertile material is the one, which can be (A) Converted into fissile material on absorption of neutron (B) Fissioned by slow (thermal) neutrons (C) Fissioned by fast neutrons

Last Answer : (A) Converted into fissile material on absorption of neutron

In β-decay of radioactive material, the ratio of neutron to proton (A) Increases (B) Remain same (C) Decreases (D) Is unpredictable; may increase or decrease

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Thorium-232 (a fertile material) on absorption of a neutron gets converted into __________ , which is a fissile material. (A) Thorium-233 (B) Uranium-235 (C) Uranium-233 (D) Plutonium-239

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Claude process of gas liquefaction employs (A) Merely compression of gas beyond its critical pressure (B) Joule-Thomson expansion cooling (C) Heat exchange with colder stream (D) Adiabatic expansion against a piston or in a turbine

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Last Answer : (D) Adiabatic expansion against a piston or in a turbine

Pick out the wrong statement pertaining to the cooling towers. (A) In case of induced draft cooling tower, the fan is placed at the top of the tower (B) Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and hot discharged air (C) A natural draft cooling tower is recommended to be used, when the air humidity is low and air temperature is also low (D) Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature

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Last Answer : (D) Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature

Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan (A) With greater number of blades (B) Of increased diameter (C) Both (A) & (B) (D) Neither (A) nor (B)

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Last Answer : (C) Both (A) & (B)

Deoiling of wax is done by its (A) Heating (B) Cooling (C) Solvent extraction (D) Both (B) & (C

Description : Deoiling of wax is done by its (A) Heating (B) Cooling (C) Solvent extraction (D) Both (B) & (C

Last Answer : (D) Both (B) & (C

Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C? (A) Humidification only (B) Heating only (C) Both heating and humidification (D) Evaporative cooling

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Last Answer : (C) Both heating and humidification

Which of the following psychrometric processes is followed by water vapour laden unsaturated air, when it is passed through solid or liquid adsorbent? (A) Cooling and dehumidification (B) Heating and dehumidification at almost constant wet bulb temperature (C) Dehumidification with dry bulb temperature remaining constant (D) None of these

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Last Answer : (B) Heating and dehumidification at almost constant wet bulb temperature

Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8 . Pr n , is not valid, if the value of (A) n = 0.4 is used for heating (B) n = 0.3 is used for cooling (C) Reynolds number for the flow involved is > 10000 (D) Reynolds number for the flow involved is < 2100

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Last Answer : (D) Reynolds number for the flow involved is < 2100

Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger calculations (Δt) weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted (D) In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

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Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

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