Engineering Chemistry Questions and Answers – Phases and Components – 1

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This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Phases and Components – 1”.

1. What is the number of phases and components present in the following reaction?
MgCO3 ⟶ MgO +CO2 (Gas)
a) 3, 2
b) 1, 3
c) 2, 3
d) 1, 2
View Answer

Answer: a
Explanation: Since we have two solids and one gaseous component in the above reaction, we have 3 phases. Also since under equilibrium, the gaseous component may evaporate, we have only two components.
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2. What is the number of phases and components in the following reaction?
NH4Cl ⟶ NH3 (Gas) + HCl (Gas)
a) 1, 2
b) 2, 1
c) 3, 1
d) 3, 2
View Answer

Answer: b
Explanation: Since we have one solid component and two gaseous components (n gaseous components contribute to one phase and n solid components contribute to n phases), we have 2 phases. Since the gaseous components may evaporate, we have only one component.

3. What is the number of phases and components in an aqueous solution of glucose?
a) 2, 1
b) 3, 2
c) 1, 3
d) 1, 2
View Answer

Answer: d
Explanation: Since we have a solid mixed in a liquid, we have two components. Since the above solution is homogeneous, we have only one phase.

4. What is the number of phases and components in the following reaction?
Fe + H2O (Gas) ⟶ FeO + H2 (Gas)
a) 3, 3
b) 2, 3
c) 1, 3
d) 2, 2
View Answer

Answer: a
Explanation: Here we have two solids and two gases, so the number of phases is two. Also the number of species is 4 (i.e N=4) and the number of reactions is one (i.e E=1). Therefore, the number of components is C = N-E = 4-1 = 3.

5. What is the number of components in a nonreactive system of KCl-NaCl-H2O?
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: c
Explanation: Since it is a nonreactive system, we should also take the ions into consideration (sodium ions, potassium ions, chlorine ions) and also the individual components (NaCl, KCl, H20). Hence N=6. Also E=3. Therefore the number of components are C = N-E = 6-3 = 3.
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6. What is the number of components present in a reactive system of NaCl-KBr-H20?
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: d
Explanation: Since it is a reactive system, we have N=9 (taking all the ions into consideration along with individual species) and also we have E=5 (considering all the neutral reactions). Therefore C = N – E = 9-5 = 4.

7. What is the degree of freedom for a water system?
a) 1
b) 2
c) 4
d) 0
View Answer

Answer: d
Explanation: We know that the number of phases and components in a water system is 3 and 1 respectively. Since it is a one component system, F = C-P+2 = 1-3+2 = 0.

8. Calculate the degree of freedom for the following reaction.
CaCO3 ⟶ CaO + CO2 (Gas)
a) 1
b) 2
c) 3
d) 0
View Answer

Answer: a
Explanation: We know that the number of phases and components in the above reaction is 3 and 2 respectively. Since it is a one component system, F = C-P+2 = 2-3+2 = 1.

9. Calculate the degree of freedom for the following reaction.
NaCl (Solid) ⟶ NaCl (Liquid) + H20 (Gas)
a) 2
b) 3
c) 1
d) 0
View Answer

Answer: c
Explanation: We know that the number of phases and components in the above reaction is 3 and 2 respectively. Since it is a one component system, F = C-P+2 = 2-3+2 = 1.
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10. Calculate the degree of freedom for an aqueous solution of glucose.
a) 1
b) 2
c) 4
d) 3
View Answer

Answer: d
Explanation: We know that the number of phases and components in the above reaction is 1 and 2 respectively. Since it is a one component system, F = C-P+2 = 2-1+2 = 3.

11. Calculate the degree of freedom for the following reaction.
N2O4 (Gas) ⟶ 2NO2 (Gas)
a) 1
b) 2
c) 3
d) 0
View Answer

Answer: b
Explanation: We know that the number of phases and components in the above reaction is 1 and 1 respectively. Since it is a one component system, F = C-P+2 = 1-1+2 = 2.

12. Calculate the degree of freedom for a saturated solution of sodium chloride.
a) 0
b) 1
c) 3
d) 2
View Answer

Answer: d
Explanation: We know that the number of phases and components in the above reaction is 2 and 2 respectively. Since it is a one-component system, F = C-P+2 = 2-2+2 = 2.

Sanfoundry Global Education & Learning Series – Engineering Chemistry.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn