Free Chemical Process Principles MCQs with Answers

• A. U-235
• B. U-238
• C. Pu-239
• D. U-239

Explanation: The neutron count is A − Z: U-235 has 143, U-238 has 146, U-239 has 147, and Pu-239 has 145. Therefore U-239 contains the most neutrons.

• A. 3.125
• B. 6.25
• C. 12.50
• D. 25

Explanation: After each half-life, half the nuclei remain, so after four half-lives the fraction is (1/2)^4 = 1/16.

• A. X
• B. Neutrons & gamma
• C. α and β
• D. Infrared

Explanation: Reactor shielding is designed mainly to attenuate penetrating gamma rays and neutrons, which can travel through substantial thicknesses of…

• A. Stainless steel
• B. Cadmium
• C. Zircaloy (an alloy of zirconium and aluminium)
• D. Graphite

Explanation: Graphite slows fast neutrons to thermal energies, increasing the probability of fission in fuels such as uranium-235.

• A. 0.01
• B. 0.25
• C. 1.2
• D. 7

Explanation: Monazite is chiefly a thorium-bearing phosphate but commonly contains about 0.1 to 0.3% uranium, making 0.25% the appropriate approximate…

• A. Pitchblende
• B. Monazite sand
• C. Limonite
• D. Galena

Explanation: Monazite sand, a phosphate mineral containing thorium and rare-earth elements, is the principal commercial ore of thorium.

• A. Radium
• B. Uranium
• C. Plutonium
• D. Neptunium

Explanation: Fast breeder reactors commonly use plutonium as fissile fuel, often in a mixed oxide fuel with uranium oxide.

• A. Use molten sodium as coolant
• B. Convert fertile material to fissile material
• C. Use fast neutrons for fission
• D. Use Th-232 as fissile fuel

Explanation: Thorium-232 is fertile rather than fissile, so it cannot normally sustain fission directly with thermal or fast neutrons; it must first…

• A. 0.71
• B. 6.31
• C. 99.29
• D. 12.73

Explanation: Natural uranium contains about 99.27% uranium-238 and only about 0.71% uranium-235, the principal naturally occurring fissile isotope.

• A. Electrometallurgical
• B. Chemical
• C. Pyrometallurgical
• D. Physical beneficiation

Explanation: Uranium extraction from ore involves chemical processing such as leaching, purification, and precipitation or solvent extraction.

• A. 1100
• B. 2200
• C. 3300
• D. 4400

Explanation: For a neutron with energy 0.025 eV, the relation E = ½mv² gives a speed of approximately 2.2 × 10³ m/s.

• A. Curie
• B. Fermi
• C. Angstrom
• D. Barn

Explanation: The curie is a traditional unit of radioactivity, representing 3.7 × 10¹⁰ nuclear disintegrations per second; the SI unit is the…

• A. Cannot attain a high temperature
• B. None of these
• C. Can produce only saturated steam for feeding to power turbine
• D. Is more efficient as gas has a higher specific heat

Explanation: Gas-cooled reactors can reach high coolant temperatures and may produce superheated rather than only saturated steam, while gases…

• A. Uranium-238
• B. Thorium-232
• C. Plutonium-239
• D. None of these

Explanation: Plutonium-239 is fissile because it can sustain a nuclear fission chain reaction with slow neutrons.

• A. 105
• B. 108
• C. 1012
• D. 1015

Explanation: An atomic radius is roughly 10⁻¹⁰ m, while a nuclear radius is about 10⁻¹⁵ m.

• A. Slows down
• B. Absorbs
• C. Accelerates
• D. Reflects

Explanation: A moderator slows fast neutrons through repeated collisions with light nuclei, increasing the likelihood of further fission in materials…

• A. α
• B. γ
• C. β
• D. α & β

Explanation: Gamma emission releases electromagnetic radiation without changing the nucleus's proton or neutron count, so the atomic number remains…

• A. Physical beneficiation
• B. Pyrometallurgical
• C. Chemical
• D. Electrometallurgical

Explanation: Uranium is generally recovered from ore by chemical processing, commonly involving leaching followed by purification and precipitation.

• A. None of these
• B. 92U235
• C. 92U234
• D. 92U238

Explanation: Natural uranium consists predominantly of uranium-238, about 99.3%, whereas uranium-235 is only about 0.7% and uranium-234 is present in…

• A. Coolant water is allowed to boil in the core of the reactor
• B. Coolant water, after being heated in the reactor core, generates steam in a boiler
• C. Pressurised water is pumped into the core
• D. Fuel and the coolant are thoroughly mixed to form a homogeneous solution

Explanation: In a boiling water reactor, water boils directly inside the reactor core and the produced steam drives the turbine.