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
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.
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
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
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
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
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.
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
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
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
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
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.
10. Calculate the degree of freedom for an aqueous solution of glucose.
a) 1
b) 2
c) 4
d) 3
View Answer
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
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
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.
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