Chemical Process Calculation Multiple Choice Questions & Answers (MCQs) focuses on “Choosing a Basis”.
1. The reference material or time selected to use in making the calculation in a problem is called
a) Basis
b) Dimension
c) Unit
d) None of the mentioned
Answer:
Clarification: The reference material or time selected to use in making the calculation in a problem is called basis.
2. What is the mass fraction of Na atom in NaOH molecule?
a) 0.33
b) 0.66
c) 0.575
d) 1.150
Answer: a
Clarification: Take basis: 1 kg mole of NaOH.
3. What is the mole fraction of Na atom in NaOH molecule?
a) 0.33
b) 0.66
c) 0.575
d) 1.150
Answer: c
Clarification: Take basis: 1 kg mole of NaOH.
4. A high energy producing gas contains the following mixtures of gases, 20% H2O, 40% CH4 and 40% CO2. The average molecular weight of the gas is?
a) 25.6
b) 26.6
c) 27.6
d) 28.6
Answer: c
Clarification: Take a basis 100 kg mole and calculate the total weight of the gas for 100 kg mole. Next step, dividing it by 100 kg mole get the molecular weight of the gas.
5-6. Consider a gas contains N2(70%), O2(25%) and SO2(5%).
5. What is the composition of the gase N2 on an SO2-free basis?
a) 0.78
b) 0.22
c) 0.70
d) 0.25
Answer: a
Clarification: First take a basis of 100 mole and then we get the moles of each gas. Next step is to eliminate 5 moles of SO2 and then calculate the composition of the gas.
6. What is the composition of the O2 gas on an SO2-free basis?
a) 0.78 and 0.22
b) 0.22 and 0.78
c) 0.70 and 0.25
d) 0.25 and 0.78
Answer: a
Clarification: First take a basis of 100 mole and then we get the moles of each gas. Next step is to eliminate 5 moles of SO2 and then calculate the composition of the gas.
7. Two students are calculating the average weight of a gas, containing N2 and other gases. Student-1 takes the actual molecular weight of N2(28) and student-2 takes it wrong N2(14). The calculated molecular weights by both of them are 36.8 and 31.2 respectively.
What is the percentage of N2 in the mixture?
a) 5%
b) 10%
c) 15%
d) 20%
Answer: b
Clarification: Take a basis of 1 mole of the gas and make two molecular weight equations, then calculate the percentage of N2.
8-10. NaOH is there in a test tube,
8. What is the mass fraction of Na in the sample?
a) 0.575
b) 0.85
c) 1.25
d) 2.28
Answer: a
Clarification: Take basis as 1 Kg mole of Na, mass fraction = 23/40.
9. What is the mass fraction of O in the sample?
a) 0.2
b) 0.4
c) 0.6
d) 0.8
Answer: b
Clarification: Take basis as 1 Kg mole of Na, mass fraction = 16/40.
10. What is the mole fraction of H in the sample?
a) 0.33
b) 0.66
c) 0.99
d) 2.00
Answer: a
Clarification: Take basis as 1 Kg mole of Na, mole fraction = 1/3.