Engineering Entrance
Q. In the reaction 2Mg + O2 → 2MgO, which element is oxidized? (2021)
A.
Magnesium
B.
Oxygen
C.
Both Magnesium and Oxygen
D.
Neither Magnesium nor Oxygen
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Solution
Magnesium is oxidized as it loses electrons and its oxidation state increases from 0 to +2.
Correct Answer: A — Magnesium
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if the volume of the container is increased? (2023)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
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Solution
According to Le Chatelier's principle, increasing the volume of the container decreases the pressure. The equilibrium will shift towards the side with more moles of gas, which is the left side (2 moles of SO2 + 1 mole of O2).
Correct Answer: B — Shift to the left
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Q. In the reaction 3H2 + N2 → 2NH3, which element is reduced? (2022)
A.
H2
B.
N2
C.
NH3
D.
None
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Solution
N2 is reduced to NH3 as it gains electrons.
Correct Answer: B — N2
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, which element is oxidized?
A.
Fe
B.
O2
C.
Fe2O3
D.
None of the above
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Solution
Iron (Fe) is oxidized as it loses electrons to form Fe2O3.
Correct Answer: A — Fe
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what effect does increasing the temperature have if the reaction is exothermic? (2020)
A.
Shifts equilibrium to the right
B.
Shifts equilibrium to the left
C.
No effect on equilibrium
D.
Increases the rate of reaction
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants, as the system tries to absorb the added heat.
Correct Answer: B — Shifts equilibrium to the left
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Q. In the reaction Zn + CuSO4 → ZnSO4 + Cu, which species is reduced?
A.
Zn
B.
CuSO4
C.
ZnSO4
D.
Cu
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Solution
Copper (Cu) is reduced as it gains electrons from zinc.
Correct Answer: D — Cu
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Q. In the redox reaction 2Ag+ + Cu → 2Ag + Cu2+, which species is oxidized? (2022) 2022
A.
Ag+
B.
Cu
C.
Ag
D.
Cu2+
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Solution
Cu is oxidized to Cu2+ as it loses electrons in the reaction.
Correct Answer: B — Cu
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Q. In the redox reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is oxidized? (2021)
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Zn is oxidized to Zn2+ as it loses electrons.
Correct Answer: B — Zn
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Q. In the redox reaction 2MnO4- + 5C2O4^2- + 16H+ → 2Mn^2+ + 10CO2 + 8H2O, what is the oxidation state of carbon in C2O4^2-?
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Solution
In C2O4^2-, the oxidation state of carbon is +3.
Correct Answer: C — +4
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Q. In which direction does the magnetic field line emerge from a bar magnet? (2022)
A.
From North to South
B.
From South to North
C.
In a circular path
D.
Randomly
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Solution
Magnetic field lines emerge from the north pole and enter the south pole of a bar magnet.
Correct Answer: A — From North to South
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Q. In which of the following processes is adsorption utilized? (2023)
A.
Water purification
B.
Sublimation
C.
Distillation
D.
Filtration
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Solution
Adsorption is widely used in water purification processes to remove impurities.
Correct Answer: A — Water purification
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Q. In which state of matter do particles have the highest energy? (2023)
A.
Solid
B.
Liquid
C.
Gas
D.
Bose-Einstein Condensate
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Solution
Gas particles have the highest energy compared to solids and liquids, allowing them to move freely and occupy more space.
Correct Answer: C — Gas
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Q. In which state of matter do particles have the least amount of energy?
A.
Solid
B.
Liquid
C.
Gas
D.
Plasma
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Solution
Particles in a solid have the least amount of energy compared to liquids, gases, and plasma.
Correct Answer: A — Solid
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Q. In which state of matter do particles move freely and are far apart? (2021)
A.
Solid
B.
Liquid
C.
Gas
D.
None of the above
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Solution
In gases, particles move freely and are far apart compared to solids and liquids.
Correct Answer: C — Gas
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Q. Solve the differential equation dy/dx = 2x + 1.
A.
y = x^2 + x + C
B.
y = x^2 + 2x + C
C.
y = 2x^2 + x + C
D.
y = x^2 + C
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Solution
Integrating both sides, we get y = ∫(2x + 1)dx = x^2 + x + C.
Correct Answer: A — y = x^2 + x + C
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Q. Solve the differential equation dy/dx = 2y + 3. (2023)
A.
y = Ce^(2x) - 3/2
B.
y = Ce^(-2x) + 3/2
C.
y = 3e^(2x)
D.
y = 2e^(2x) + C
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Solution
Using an integrating factor, we find the solution is y = Ce^(2x) - 3/2.
Correct Answer: A — y = Ce^(2x) - 3/2
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Q. Solve the differential equation dy/dx = y/x. (2023)
A.
y = Cx
B.
y = Cx^2
C.
y = C/x
D.
y = C ln(x)
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Solution
This is a separable equation. Integrating gives y = Cx.
Correct Answer: A — y = Cx
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Q. Solve the differential equation y' = 5 - 2y.
A.
y = 5/2 + Ce^(-2x)
B.
y = 5 + Ce^(-2x)
C.
y = 2 + Ce^(2x)
D.
y = 5/2 - Ce^(-2x)
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Solution
This is a linear first-order equation. The solution is y = 5/2 + Ce^(-2x).
Correct Answer: A — y = 5/2 + Ce^(-2x)
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Q. Solve the differential equation y' = 5y + 3.
A.
y = (3/5) + Ce^(5x)
B.
y = (5/3) + Ce^(5x)
C.
y = Ce^(5x) - 3
D.
y = Ce^(3x) + 5
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Solution
Using the integrating factor method, we find the solution y = (3/5) + Ce^(5x).
Correct Answer: A — y = (3/5) + Ce^(5x)
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Q. Solve the differential equation y'' - 3y' + 2y = 0.
A.
y = C1e^(2x) + C2e^(x)
B.
y = C1e^(x) + C2e^(2x)
C.
y = C1e^(-x) + C2e^(-2x)
D.
y = C1e^(3x) + C2e^(x)
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Solution
The characteristic equation is r^2 - 3r + 2 = 0, which factors to (r - 1)(r - 2) = 0. The general solution is y = C1e^(x) + C2e^(2x).
Correct Answer: B — y = C1e^(x) + C2e^(2x)
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Q. Solve the equation y' = 6y + 12.
A.
y = 2 - Ce^(-6x)
B.
y = Ce^(6x) - 2
C.
y = 2 + Ce^(6x)
D.
y = 6Ce^(-x)
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Solution
This is a first-order linear equation. The integrating factor method gives the solution y = 2 - Ce^(-6x).
Correct Answer: A — y = 2 - Ce^(-6x)
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Q. Solve the first-order differential equation dy/dx = y/x.
A.
y = Cx
B.
y = Cx^2
C.
y = C/x
D.
y = C ln(x)
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Solution
This is a separable equation. Separating variables and integrating gives y = Cx.
Correct Answer: A — y = Cx
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Q. Solve the first-order linear differential equation dy/dx + y/x = 1.
A.
y = x + C/x
B.
y = Cx - x
C.
y = Cx + x
D.
y = C/x + x
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Solution
Using the integrating factor e^(∫(1/x)dx) = x, we solve to get y = x + C/x.
Correct Answer: A — y = x + C/x
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Q. The Arrhenius equation relates which of the following? (2023)
A.
Rate constant and temperature
B.
Concentration and time
C.
Pressure and volume
D.
Energy and temperature
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Solution
The Arrhenius equation relates the rate constant (k) to temperature (T) and activation energy (Ea).
Correct Answer: A — Rate constant and temperature
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Q. The dimensional formula for frequency is: (2023)
A.
[T^-1]
B.
[M^0 L^0 T^-1]
C.
[M^1 L^1 T^-1]
D.
[M^0 L^1 T^0]
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Solution
Frequency is defined as the number of cycles per unit time, hence its dimensional formula is [T^-1].
Correct Answer: A — [T^-1]
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Q. The dimensional formula for velocity is: (2022)
A.
[M^0 L^1 T^-1]
B.
[M^1 L^1 T^0]
C.
[M^1 L^0 T^-1]
D.
[M^0 L^0 T^1]
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Solution
Velocity is defined as displacement per unit time, hence its dimensional formula is [M^0 L^1 T^-1].
Correct Answer: A — [M^0 L^1 T^-1]
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Q. The force on a charged particle moving in a magnetic field is maximum when the angle between the velocity and the magnetic field is: (2021)
A.
0 degrees
B.
90 degrees
C.
180 degrees
D.
45 degrees
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Solution
The force on a charged particle moving in a magnetic field is maximum when the angle between the velocity and the magnetic field is 90 degrees.
Correct Answer: B — 90 degrees
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Q. The force on a charged particle moving in a magnetic field is maximum when: (2021)
A.
The particle moves parallel to the field
B.
The particle moves perpendicular to the field
C.
The particle is at rest
D.
The particle moves in a circular path
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Solution
The force on a charged particle moving in a magnetic field is maximum when the particle moves perpendicular to the field.
Correct Answer: B — The particle moves perpendicular to the field
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Q. The frequency of a tuning fork is 440 Hz. What is the time period of the sound wave produced? (2022)
A.
0.00227 s
B.
0.0045 s
C.
0.01 s
D.
0.005 s
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Solution
Time period (T) = 1 / frequency (f) = 1 / 440 Hz ≈ 0.00227 s.
Correct Answer: A — 0.00227 s
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Q. The half-life of a first-order reaction is dependent on which of the following? (2020) 2020
A.
Initial concentration of reactants
B.
Rate constant
C.
Temperature
D.
All of the above
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Solution
The half-life of a first-order reaction is independent of the initial concentration and is directly proportional to the rate constant.
Correct Answer: B — Rate constant
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