Engineering Chemistry MCQ (Phase and Components-01)

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Engineering Chemistry MCQ (Phases and Components)

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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
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.

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
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
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
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
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.

6. What is the number of components present in a reactive system of NaCl-KBr-H20?a) 1
b) 2
c) 3
d) 4
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
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
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
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.

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