Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) on “Problem Solving Strategy”.
1. Solution-1 at the rate F combines with solution-2 at the rate D, their combination gives the product at the rate P, what is the equation of material balance?
a) F + D = P
b) F – P = D
c) D – F = P
d) None of the mentioned
Answer: a
Clarification: The general equation of material balance is F + D = P.
2. Solution-1 containing 30% sulfuric acid flowing at the rate 10 Kg/min combines with Solution-2 containing 20% sulfuric acid flowing at the rate 5 Kg/min, if their product is out at the rate 20 Kg/min what is the percentage of sulfuric acid in the product?
a) 10%
b) 20%
c) 30%
d) 40%
Answer: b
Clarification: Equation of material balance, 0.3(10) + 0.2(5) = x(20), => x = 0.2, => Percentage of sulfuric acid in the product = 20%.
3. Solution-1 containing 10% nitric acid flowing at the rate 10 Kg/min combines with Solution-2 containing 40% nitric acid flowing at the rate 5 Kg/min, if their product contains 30% nitric acid, what is the flow rate of product?
a) 10 Kg/min
b) 20 Kg/min
c) 30 Kg/min
d) 40 Kg/min
Answer: a
Clarification: Equation of material balance, 0.1(10) + 0.4(5) = 0.3(x), => x = 10 Kg/min.
4. Solution-1 containing 10% nitric acid and 20% acetic acid at the rate F combines with Solution-2 containing 20% nitric acid and 10% acetic acid at the rate D, the product formed contains 30% nitric acid and 20% acetic acid at the rate P, how many independent equations containing F, D, and P are possible?
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: The equations of material balance are: 0.1F + 0.2D = 0.3P, 0.2F + 0.1D = 0.2P, and F + D = P.
5. Solution-1 containing 10% hydrochloric acid and 20% acetic acid at the rate F combines with Solution-2 containing 20% hydrochloric acid and 30% acetic acid at the rate D, the product formed contains 20% hydrochloric acid and 30% acetic acid at the rate P, how many independent equations containing F, D, and P are possible?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: The equations of material balance are: 0.1F + 0.2D = 0.2P, 0.2F + 0.3D = 0.3P and F + D = P, but if we subtract first two of them then we get the third, so number of independent equations are 2.
6. Solution-1 containing 40% nitric acid and 20% carbon dioxide at the rate F combines with Solution-2 containing 30% nitric acid and 40% carbon dioxide at the rate D, the product formed contains 30% nitric acid and 20% carbon dioxide at the rate P, If P = xF what is x?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: The equations of material balance are: 0.4F + 0.2D = 0.3P, 0.2F + 0.4D = 0.3P, and F + D = P, Solving these we get D = F = P/2, => x = 2.
7. Solution-1 containing 40% acetic acid and 20% carbon dioxide at the rate F combines with Solution-2 containing 20% acetic acid and 40% carbon dioxide at the rate D, the product formed contains 30% acetic acid at the rate P, what is the percentage of carbon dioxide in product?
a) 10%
b) 20%
c) 30%
d) 40%
Answer: c
Clarification: The equations for material balance are: 0.4F + 0.2D = 0.3P, F + D = P, and 0.2F + 0.4D = yP, solving these we get y = 0.3, => percentage of carbon dioxide = 30%.
8. Solution-1 containing 20% w1 and w2 at the rate 10 Kg/min combines with Solution-2 containing 10% w1, 20% w2 and w3 at the rate 20 Kg/min, the product formed contains and 10% w1, 30% w2 and 20% w3, what is the percentage of w2 in solution-1?
a) 5%
b) 10%
c) 25%
d) 50%
Answer: d
Clarification: Rate of product, P = 10 + 20 = 30 Kg/min, equation of material balance for w2: x(10) + 0.2(20) = 0.3(30), => w2 = 0.5, => percentage of w2 = 50%.
9. CH4 at the rate 10 mole/min is reacted with O2 at the rate 10 mole/min, what is the rate of formation of CO2 in the product?
a) 5 mole/min
b) 10 mole/min
c) 20 mole/min
d) 40 mole/min