All Free Chemical Engineering MCQs with Answers

• A. Economic power generation
• B. Power generation on commercial scale
• C. Sustainment of chain reaction
• D. None of these

Explanation: Critical mass is the smallest quantity of fissile material in which each generation of neutrons can produce enough further fissions to…

• A. Isomers
• B. Isotopes
• C. Isobars
• D. Isotones

Explanation: The mass number minus the atomic number equals the number of neutrons. Atoms of different elements with the same neutron number are called…

• A. Curie
• B. MeV
• C. Barn
• D. Ergs

Explanation: Radioactivity means the activity or rate of nuclear disintegration, traditionally measured in curies, while the becquerel is the SI unit.

• A. 1/4
• B. 1/16
• C. 1/2
• D. 1/8

Explanation: Four hundred days contain four half-lives of 100 days, so the amount becomes 1 × (1/2)^4 = 1/16 gram.

• A. α & β
• B. γ & α
• C. β & γ
• D. α, β, & γ

Explanation: Beta emission changes a neutron into a proton or vice versa, so the mass number remains unchanged; gamma emission also leaves both mass…

• A. Temperature
• B. Pressure
• C. Amount of element present
• D. None of these

Explanation: For a given radioactive isotope, half-life is a nuclear property and is essentially independent of temperature, pressure and the amount of…

• A. Temperature
• B. Pressure
• C. Amount
• D. None of these

Explanation: The half-life is fixed by the decay constant of the isotope, so it does not depend on temperature, pressure or the quantity present.

• A. Fuel elements
• B. Operating personnels
• C. Walls of the reactor

Explanation: The biological shield is a thick concrete or equivalent barrier placed around the reactor to absorb penetrating radiation and protect…

• A. Lower density
• B. Higher specific heat
• C. Non-reactivity to uranium
• D. Lower neutron capture cross-section

Explanation: Hydrogen has a much higher specific heat than carbon dioxide, so it can carry more heat per unit mass for the same temperature rise.

• A. Kinetic energy of neutrons
• B. Radioactive decay of fission products
• C. Instantaneous release of γ-rays
• D. Kinetic energy of fission products

Explanation: Most fission energy appears immediately as the kinetic energy of the two heavy fission fragments, which rapidly becomes heat in the fuel.

• A. 159
• B. 1837
• C. 2537
• D. 10000

Explanation: A proton and neutron have nearly equal masses, so the proton-to-electron mass ratio is also about 1837 to 1839.

• A. Uranium oxide
• B. Uranium hexafluoride
• C. Uranium carbide
• D. Uranium sulphate

Explanation: Uranium is converted to uranium hexafluoride, UF₆, because it is sufficiently volatile to form a gas for isotope separation.

• A. U-238
• B. U-233
• C. U-235
• D. Pu-239

Explanation: Natural uranium contains mostly U-238 and only about 0.7% U-235, so enrichment increases the concentration of the fissile isotope U-235.

• A. None of these
• B. Working fluid in power turbine
• C. Moderator
• D. Coolant

Explanation: In a PWR, pressurised water circulates through the reactor core as coolant and also serves as moderator.

• A. More than
• B. Less than
• C. Equal to
• D. Either more or less

Explanation: Fission becomes energetically possible when the excitation or critical energy exceeds the neutron binding energy of the compound nucleus.

• A. No
• B. One
• C. Three
• D. Two

Explanation: Hydrogen has three naturally recognised isotopes: protium, deuterium, and tritium. They all contain one proton but differ in neutron number.

• A. Boron hydride
• B. Light water
• C. Beryllium
• D. Molten sodium

Explanation: Molten sodium is commonly used as a reactor coolant, not as a neutron moderator.

• A. U-238
• B. U-235
• C. U-233
• D. Pu-239

Explanation: U-233, U-235, and Pu-239 are fissile because they can sustain a chain reaction with slow neutrons.

• A. Plutonium
• B. Thorium
• C. Uranium
• D. None of these

Explanation: India has very large thorium reserves, while its uranium resources are comparatively limited.

• A. 1836 (approximately)
• B. 1
• C. 1/1836 (approximately)
• D. ∞

Explanation: An electron is about 1836 times lighter than a proton, so its mass is approximately 1/1836 of the proton mass.