All Free Chemical Engineering MCQs with Answers
Every Chemical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
6,983 questions · page 104 of 350
- A. gram
- B. Kilogram
- C. gm.mole
- D. Litre
Explanation: Avogadro’s number is the number of molecules in one gram-mole, also called one mole, of a substance.
Correct answer: gm.mole- A. 350
- B. 485
- C. 140
- D. 345
Explanation: Hardness is due mainly to multivalent ions such as Ca²⁺, while Na⁺ does not contribute appreciably to hardness.
Correct answer: 350- A. 760 torr
- B. 10 metres of water column
- C. 1 KPa
- D. 1 metre of water column
Explanation: A pressure of 1 kgf/cm² is approximately 98.1 kPa. Since a 10 m water column produces about 98 kPa, it is equivalent to approximately 10…
Correct answer: 10 metres of water column2064. The hydroxyl ion (OH-) concentration in a solution having pH value 3 will be_________________?
- A. 10-3
- B. 10-10
- C. 10-11
- D. 10-4
Explanation: At 25°C, pH + pOH = 14, so pOH = 14 − 3 = 11. Therefore, the hydroxyl-ion concentration is approximately 10⁻¹¹ mol/L.
Correct answer: 10-11- A. 1/2
- B. 2/3
- C. 1/4
- D. 1/3
Explanation: At the same temperature and volume, pressure fraction equals mole fraction.
Correct answer: 1/3- A. Recycle stream/fresh feed stream
- B. Gross feed stream/recycle feed stream
- C. Recycle stream/gross feed stream
- D. None of these
Explanation: The recycle ratio compares the stream returned to the process with the fresh feed entering it, commonly written as recycle flow divided by…
Correct answer: Recycle stream/fresh feed stream- A. 80%
- B. 90%
- C. 95%
- D. 98%
Explanation: Pure urea contains 28/60 = 46.67% nitrogen by mass. Thus a sample containing 42% nitrogen has urea purity equal to 42/46.67 × 100 = 90%.
Correct answer: 90%- A. Atomic weight of the metal is 4
- B. Equivalent weight of the metal is 4
- C. Atomic weight of the metal is 2
- D. Equivalent weight of the metal is 8
Explanation: The oxide contains 3.15 − 1.05 = 2.10 g oxygen. Using 8 g oxygen per equivalent, the metal equivalent weight is 1.05 × 8/2.10 = 4; its…
Correct answer: Equivalent weight of the metal is 42069. Which of the following expressions defines the Baume gravity scale for liquids heavier than water ?
- A. (141.5/G) - 131.5
- B. (400/G) - 400
- C. 200 (G-1)
- D. 145 - (145/G)
Explanation: For liquids heavier than water, the Baumé scale is defined as 145 − 145/G, where G is the specific gravity.
Correct answer: 145 - (145/G)- A. Facilitates better control of the process
- B. Improves the conversion
- C. Increases the yield of products
- D. None of these
Explanation: A bypass divides flow around a unit, allowing the fraction passing through the unit to be adjusted and the process conditions to be…
Correct answer: Facilitates better control of the process- A. With chemical reaction
- B. Without chemical reaction & losses
- C. Without chemical reaction
- D. None of these
Explanation: At steady state there is no accumulation, but reactions or losses add generation or disappearance terms to the balance.
Correct answer: Without chemical reaction & losses- A. Input
- B. Production
- C. Accumulation
- D. Generation
Explanation: At steady state, the amount of material inside the system does not change with time, so the accumulation term in the material balance is…
Correct answer: Accumulation- A. Remain unaltered
- B. Decrease three fold
- C. Increase three fold
- D. Increase nine fold
Explanation: For a fixed amount of ideal gas, volume varies directly with absolute temperature and inversely with pressure: V ∝ T/P.
Correct answer: Increase nine fold- A. W/m2.°K
- B. J/kg.°K
- C. W/m.°K
- D. J/m3. °K
Explanation: Specific heat capacity Cp is energy required per unit mass per unit temperature rise, giving the SI unit J/(kg·K).
Correct answer: J/kg.°K- A. 53
- B. 5.3
- C. 106
- D. 10.6
Explanation: The intended product is NaHCO₃, representing the first neutralization step in which one mole of Na₂CO₃ accepts one mole of H⁺.
Correct answer: 106- A. 0.19
- B. 0.33
- C. 0.40
- D. 0.67
Explanation: The products contain 1 mol of CO₂, 2 mol of H₂O, and about 7.52 mol of N₂ from the stoichiometric air. Thus, yH₂O = 2/(1 + 2 + 7.52) ≈ 0.19.
Correct answer: 0.19- A. Lower than
- B. Higher than
- C. Same as
- D. Not related to
Explanation: Air contains nitrogen that dilutes the reactants and absorbs heat without contributing to combustion, reducing the flame temperature.
Correct answer: Lower than- A. Recycling
- B. Purging
- C. Bypassing
- D. Recirculation
Explanation: Purging removes a portion of an outlet or recycle stream to prevent inert impurities from accumulating in the process.
Correct answer: Purging- A. Nature
- B. Size
- C. Absolute temperature
- D. All A., B. & C.
Explanation: By kinetic theory, the average translational kinetic energy of gas molecules is proportional to absolute temperature, specifically 3RT/2…
Correct answer: Absolute temperature- A. 14
- B. 2.5
- C. 28
- D. 1.25
Explanation: At NTP, nitrogen occupies about 22.4 L per mole, while one mole of N₂ weighs 28 g. Thus, 2 L weighs 28(2/22.4), approximately 2.5 g.
Correct answer: 2.5