1. Which of the following is the example of Reflexivity equivalence relation?
a) A ∼ A
b) A ∼ B
c) A ∼ C
d) C ∼ B
Explanation: The equivalence relation is of reflexivity as an example of a reflexive relation is the relation “is equal to” on the set of real numbers since every real number is equal to itself. A reflexive relation is said to have the reflexive property or is said to possess reflexivity. Along with symmetry and transitivity, reflexivity is one of three properties defining equivalence relations.
2. Conversion of 40°C into Fahrenheit.
a) 40 F
b) 100 F
c) 4 F
d) 104 F
Explanation: T(°F) = T(°C) × 9/5 + 32
= 40 × 9/5 + 32
= 104 F.
3. Conversion of 40 K into Celsius.
a) -233.15 °C
b) 233.15 °C
c) –245 °C
d) 245 °C
Explanation: T(°C) = T(K) – 273.15
= 40 – 273.15
= -233.15 °C.
4. Two metal strips that constitute a thermostat must necessarily differ in their _______________
a) Mass
b) Length
c) Resistivity
d) Coefficient of linear expansion
Explanation: Thermostat is used in electric apparatus like a refrigerator, Iron etc for automatic cut off. Therefore for metallic strips to bend on heating their coefficient of linear expansion should be different.
5. Which is the correct order for the equation of mass balance of the system?
{A} – {B} + {C} – {D} = {Mass accumulated within system}
a) A. Mass consumed within system, B. Mass in through system boundaries, C. Mass out through system boundaries, D. Mass generated within system
b) A. Mass generated within system, B. Mass in through system boundaries, C. Mass out through system boundaries, D. Mass consumed within system
c) A. Mass in through system boundaries, B. Mass out through system boundaries, C. Mass generated within system, D. Mass consumed within system
d) A. Mass consumed within system, B. Mass generated within system, C. Mass out through system boundaries, D. Mass in through system boundaries
Explanation: A mass balance for the system can be written in a general way to account for these possibilities:
{Mass in through system boundaries} – {Mass out through system boundaries} + {Mass generated within system} – {Mass consumed within system} = {Mass accumulated within system}.
6. If the Reactant iron is combined with Reactant Sulfur to form the product Iron sulfide, then what will be the atomic mass of the product?
a) 88
b) 44
c) 22
d) 80
Explanation: Fe (iron) + S (Sulfur) = FeS (Iron sulfide),
Atomic masses: Fe = 56, S = 32
One atom of each element on each side of the equations
Law of conservation of mass balance: 56 + 32 = 88.
7. If the reactant Magnesium reacts with Reactant Hydrochloric acid to form the product Magnesium chloride + Hydrogen, then what will be the atomic mass of both the product?
a) 90
b) 97
c) 80
d) 87
Explanation: Mg (Magnesium) + 2 HCl (Hydrochloric acid) = MgCl2 (Magnesium chloride) + H2 (Hydrogen),
Atomic masses: Mg = 24, H = 1, Cl = 35.5
one atom of Mg, 2 atoms of H and 2 atoms of Cl on both sides of the equation,
Law of conservation of mass balance: 24 + 2 × (1+ 35.5) = 24+ (2 × 35.5) + (2×1) = 97 (Both equal 97)
Note the subscript 2 after the Cl in magnesium chloride or the 2 after the H in the hydrogen molecule, means two atoms of that element.
The 2 before the HCl doubles the number of hydrochloric acid molecules.
8. A continuous process is set up for treatment of wastewater. Each day, 103 kg cellulose and 105 kg bacteria enter in the feed stream, while 102 kg cellulose and 1.5 x 102 kg bacteria leave in the effluent. The rate of cellulose digestion by the bacteria is 8 x 102 kg d-1. The rate of bacterial growth is 4x 102 kg d-l; the rate of cell death by lysis is 6 x 102 kg d-1. Write balances for cellulose and bacteria in the system.
a) 1× 103 kg, 9 × 103 kg
b) 1× 102 kg, 9.965 × 104 kg
c) 1× 103 kg, 9.964 × 104 kg
d) 1× 102 kg, 9 × 103 kg
Explanation: Cellulose is not generated by the process, only consumed. Using a basis of 1 day, the cellulose balance in kg is :
(103 – 102 + 0 – 8 x 102) = accumulation
Therefore, 1× 102 kg cellulose accumulates in the system each day.
Performing the same balance for bacteria:
(105 – 1.5 x 102 + 4 x 102 – 6 x 102) = accumulation
Therefore, 9.965 × 104 kg bacterial cells accumulate in the system each day.
9. Which of the following system follows the differential equation?
a) Semi- Batch process
b) Batch process
c) Fed- Batch process
d) Continuous process
Explanation: Amounts of mass entering and leaving the system are specified using flow rates, a mass balance based on rates is called a differential balance. Whereas, each term of the mass-balance equation in this case is a quantity of mass, not a rate. This type of balance is called an integral balance. Differential balances for continuous systems operating at steady state and integral balances for batch and semi-batch systems between initial and final states are used.
10. 2SO2+O2 → 2SO3. What is the stoichiometric ratio of SO2 to SO3?
a) 3
b) 1
c) 2
d) 0
Explanation: stoichiometric ratio of SO2 to SO3 = (2 mole of SO2 reacted)/(2 mole of SO3 produced) = 1.