Q. In a p-n junction, which type of charge carriers are predominant in the p-type region? (2019)
A.
Electrons
B.
Holes
C.
Protons
D.
Neutrons
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Solution
In a p-type region, holes are the predominant charge carriers.
Correct Answer: B — Holes
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Q. In a pedigree chart, a filled circle represents which of the following? (2023)
A.
Male
B.
Female
C.
Affected female
D.
Affected male
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Solution
In a pedigree chart, a filled circle represents an affected female.
Correct Answer: C — Affected female
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Q. In a PN junction diode, the depletion region is formed due to: (2019)
A.
Excess electrons
B.
Excess holes
C.
Recombination of electrons and holes
D.
External voltage
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Solution
The depletion region in a PN junction diode is formed due to the recombination of electrons and holes at the junction.
Correct Answer: C — Recombination of electrons and holes
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Q. In a PN junction diode, what happens when it is forward biased? (2019)
A.
Depletion region widens
B.
Depletion region narrows
C.
No current flows
D.
Reverse current increases
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Solution
When a PN junction diode is forward biased, the depletion region narrows, allowing current to flow.
Correct Answer: B — Depletion region narrows
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Q. In a PN junction, what is formed at the junction of p-type and n-type materials? (2021)
A.
Electric field
B.
Magnetic field
C.
Thermal field
D.
Gravitational field
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Solution
An electric field is formed at the junction of p-type and n-type materials due to the diffusion of charge carriers.
Correct Answer: A — Electric field
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Q. In a PN junction, what is the region called where no charge carriers are present? (2019)
A.
Depletion region
B.
Conduction band
C.
Valence band
D.
Neutral zone
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Solution
The depletion region is the area around the PN junction where no free charge carriers are present.
Correct Answer: A — Depletion region
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Q. In a predator-prey relationship, what is the primary effect of an increase in the prey population? (2021)
A.
Decrease in predator population
B.
Increase in predator population
C.
Decrease in prey population
D.
No effect on predator population
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Solution
An increase in the prey population typically leads to an increase in the predator population due to more available food.
Correct Answer: B — Increase in predator population
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Q. In a predator-prey relationship, which of the following is true? (2022)
A.
Predators are always larger than their prey.
B.
Prey populations are always larger than predator populations.
C.
Predators help control prey populations.
D.
Prey can never escape predators.
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Solution
Predators help control the population of prey species, maintaining a balance in the ecosystem.
Correct Answer: C — Predators help control prey populations.
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Q. In a ray diagram for a concave lens, the rays parallel to the principal axis appear to diverge from which point? (2021)
A.
Focal point
B.
Center of curvature
C.
Optical center
D.
Principal focus
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Solution
In a ray diagram for a concave lens, rays parallel to the principal axis appear to diverge from the focal point.
Correct Answer: A — Focal point
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Q. In a reaction at equilibrium, if the concentration of a reactant is increased, what will happen to the equilibrium position? (2019)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on temperature
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Solution
Increasing the concentration of a reactant will shift the equilibrium position to the right, favoring the formation of products.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the concentration of products is increased, what will happen? (2022)
A.
Equilibrium shifts to the left
B.
Equilibrium shifts to the right
C.
No change
D.
Reaction stops
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Solution
According to Le Chatelier's principle, increasing the concentration of products will shift the equilibrium to the left, favoring the formation of reactants.
Correct Answer: A — Equilibrium shifts to the left
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Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the position of equilibrium? (2022)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on temperature
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Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to produce more products.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the temperature is increased and the reaction is exothermic, what will happen? (2021)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in Kc
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants.
Correct Answer: B — Shift to the left
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Q. In a reaction at equilibrium, if the temperature is increased for an exothermic reaction, what will happen? (2022)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in pressure
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants.
Correct Answer: B — Shift to the left
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Q. In a reaction, if the concentration of reactants is doubled, what happens to the rate of reaction if it is first order? (2023)
A.
Doubles
B.
Triples
C.
Quadruples
D.
Remains the same
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Solution
For a first-order reaction, the rate is directly proportional to the concentration of the reactant, so doubling the concentration doubles the rate.
Correct Answer: A — Doubles
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Q. In a redox reaction, if the oxidation state of an element decreases, what happens to that element? (2021)
A.
It is oxidized
B.
It is reduced
C.
It remains unchanged
D.
It is ionized
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Solution
A decrease in oxidation state indicates that the element has gained electrons, which means it is reduced.
Correct Answer: B — It is reduced
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Q. In a redox reaction, if the oxidation state of an element decreases, what has occurred? (2021)
A.
Oxidation
B.
Reduction
C.
Neutralization
D.
Decomposition
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Solution
A decrease in oxidation state indicates that the element has gained electrons, which is defined as reduction.
Correct Answer: B — Reduction
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Q. In a redox reaction, if the oxidation state of an element decreases, what is happening to that element? (2021)
A.
It is being oxidized
B.
It is being reduced
C.
It is unchanged
D.
It is ionized
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Solution
A decrease in oxidation state indicates that the element is gaining electrons, which means it is being reduced.
Correct Answer: B — It is being reduced
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Q. In a redox reaction, if the oxidation state of an element increases, what happens to that element? (2021)
A.
It is oxidized
B.
It is reduced
C.
It remains unchanged
D.
It forms a compound
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Solution
An increase in the oxidation state of an element indicates that it has lost electrons, which means it is oxidized.
Correct Answer: A — It is oxidized
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Q. In a redox reaction, what happens to the oxidation state of the reducing agent? (2021)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Varies
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Solution
The oxidation state of the reducing agent decreases as it loses electrons during the reaction.
Correct Answer: B — Decreases
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Q. In a redox reaction, which of the following statements is true? (2020)
A.
Oxidation involves gain of electrons
B.
Reduction involves loss of electrons
C.
Oxidation state of an element decreases during oxidation
D.
Reduction involves gain of electrons
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Solution
Reduction is defined as the gain of electrons, which decreases the oxidation state of the element.
Correct Answer: D — Reduction involves gain of electrons
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Q. In a reversible process, the work done is: (2023)
A.
Always maximum
B.
Always minimum
C.
Equal to the heat absorbed
D.
Independent of the path
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Solution
In a reversible process, the work done is always maximum compared to irreversible processes.
Correct Answer: A — Always maximum
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Q. In a reversible reaction at equilibrium, what happens if the temperature is increased? (2019)
A.
The reaction shifts to the exothermic side
B.
The reaction shifts to the endothermic side
C.
No change occurs
D.
The reaction rate decreases
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Solution
Increasing the temperature of an exothermic reaction shifts the equilibrium to the left (towards the reactants), while for an endothermic reaction, it shifts to the right (towards the products).
Correct Answer: B — The reaction shifts to the endothermic side
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Q. In a reversible reaction, if the forward reaction is exothermic, what can be said about the reverse reaction? (2022)
A.
It is also exothermic
B.
It is endothermic
C.
It has no effect on equilibrium
D.
It is spontaneous
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Solution
If the forward reaction is exothermic, the reverse reaction must be endothermic, as it absorbs heat.
Correct Answer: B — It is endothermic
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Q. In a series circuit with a 12V battery and two resistors of 4Ω and 8Ω, what is the voltage across the 8Ω resistor? (2022)
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Solution
Total resistance R_total = 4Ω + 8Ω = 12Ω. Current I = V/R_total = 12V/12Ω = 1A. Voltage across 8Ω = I * R = 1A * 8Ω = 8V.
Correct Answer: B — 6V
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Q. In a series circuit with a 9V battery and three resistors of 1Ω, 2Ω, and 3Ω, what is the total resistance? (2019)
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Solution
Total resistance in series is R_total = R1 + R2 + R3 = 1 + 2 + 3 = 6Ω.
Correct Answer: A — 6Ω
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Q. In a series circuit, if one resistor fails, what happens to the current in the circuit? (2019)
A.
It increases
B.
It decreases
C.
It stops
D.
It remains the same
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Solution
In a series circuit, if one resistor fails, the circuit is broken and the current stops.
Correct Answer: C — It stops
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Q. In a series circuit, if one resistor is removed, what happens to the current? (2023)
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
In a series circuit, removing one resistor breaks the circuit, causing the current to become zero.
Correct Answer: D — It becomes zero
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Q. In a series circuit, if the resistance is doubled, what happens to the current flowing through the circuit? (2021)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It becomes zero
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Solution
According to Ohm's law, I = V/R. If R is doubled, the current I will be halved for a constant voltage V.
Correct Answer: B — It halves
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Q. In a series RLC circuit, at resonance, the impedance is equal to which of the following? (2020)
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Solution
At resonance in a series RLC circuit, the impedance (Z) is equal to the resistance (R) because the inductive and capacitive reactances cancel each other out.
Correct Answer: B — R
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