Q. What is the role of a diode in a circuit?
A.
Resistor
B.
Capacitor
C.
Current regulator
D.
Current rectifier
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Solution
A diode acts as a current rectifier, allowing current to flow in one direction while blocking it in the opposite direction.
Correct Answer: D — Current rectifier
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Q. What is the role of a diode in a semiconductor circuit?
A.
Amplification
B.
Rectification
C.
Oscillation
D.
Capacitance
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Solution
A diode is primarily used for rectification, allowing current to flow in one direction only.
Correct Answer: B — Rectification
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Q. What is the role of a fuse in an electrical circuit?
A.
To increase current
B.
To decrease voltage
C.
To protect against overload
D.
To store energy
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Solution
A fuse is designed to protect the circuit by breaking the connection when the current exceeds a certain limit.
Correct Answer: C — To protect against overload
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Q. What is the role of a moderator in a nuclear reactor?
A.
To absorb neutrons
B.
To slow down neutrons
C.
To increase the temperature
D.
To shield radiation
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Solution
The role of a moderator in a nuclear reactor is to slow down neutrons, making them more likely to induce fission in the fuel.
Correct Answer: B — To slow down neutrons
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Q. What is the role of a p-n junction in a semiconductor device?
A.
To increase resistance
B.
To create a depletion region
C.
To enhance thermal conductivity
D.
To reduce current flow
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Solution
A p-n junction creates a depletion region which is essential for the operation of diodes and transistors.
Correct Answer: B — To create a depletion region
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Q. What is the role of a salt bridge in a galvanic cell?
A.
To provide a pathway for electrons
B.
To maintain charge balance
C.
To increase voltage
D.
To decrease resistance
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Solution
The salt bridge maintains charge balance by allowing ions to flow between the two half-cells.
Correct Answer: B — To maintain charge balance
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Q. What is the role of a semiconductor in a transistor?
A.
To store charge
B.
To amplify current
C.
To insulate
D.
To generate heat
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Solution
In a transistor, the semiconductor material is used to amplify current, allowing small input signals to control larger output signals.
Correct Answer: B — To amplify current
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Q. What is the role of a transistor in electronic circuits?
A.
Switching
B.
Amplification
C.
Signal modulation
D.
All of the above
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Solution
Transistors can perform multiple functions including switching, amplification, and signal modulation.
Correct Answer: D — All of the above
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Q. What is the role of a transponder in satellite communication?
A.
To amplify the received signal
B.
To convert signals from one frequency to another
C.
To modulate the signal for transmission
D.
To demodulate the received signal
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Solution
A transponder receives signals at one frequency, amplifies them, and then converts them to another frequency for transmission back to Earth.
Correct Answer: B — To convert signals from one frequency to another
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Q. What is the role of activated charcoal in adsorption processes?
A.
Catalyst
B.
Adsorbent
C.
Solvent
D.
Reagent
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Solution
Activated charcoal is commonly used as an adsorbent due to its high surface area and porosity.
Correct Answer: B — Adsorbent
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Q. What is the role of antioxidants in food?
A.
Enhancing flavor
B.
Preventing spoilage
C.
Reducing oxidation
D.
Increasing acidity
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Solution
Antioxidants prevent oxidation, which can spoil food and reduce its nutritional value.
Correct Answer: C — Reducing oxidation
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Q. What is the role of antioxidants in the body?
A.
Increase energy
B.
Prevent oxidation
C.
Enhance digestion
D.
Boost immunity
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Solution
Antioxidants prevent oxidation, which can damage cells and lead to various diseases.
Correct Answer: B — Prevent oxidation
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Q. What is the role of ATP in cells?
A.
Storage of genetic information
B.
Energy currency
C.
Structural component
D.
Signal transduction
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Solution
ATP (adenosine triphosphate) serves as the primary energy currency in cells.
Correct Answer: B — Energy currency
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Q. What is the role of caffeine in coffee?
A.
Antioxidant
B.
Stimulant
C.
Sedative
D.
Digestive aid
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Solution
Caffeine acts as a stimulant, increasing alertness and reducing fatigue.
Correct Answer: B — Stimulant
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Q. What is the role of chlorofluorocarbons (CFCs) in environmental chemistry?
A.
Ozone depletion
B.
Greenhouse gas effect
C.
Acid rain formation
D.
Water pollution
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Solution
CFCs are known to deplete the ozone layer, leading to increased UV radiation reaching the Earth's surface.
Correct Answer: A — Ozone depletion
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Q. What is the role of coherence in interference phenomena?
A.
It determines the intensity of light
B.
It ensures constant phase difference
C.
It affects the wavelength
D.
It changes the speed of light
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Solution
Coherence refers to the constant phase relationship between waves, which is essential for producing stable interference patterns.
Correct Answer: B — It ensures constant phase difference
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Q. What is the role of emulsifiers in food products?
A.
Thickeners
B.
Stabilizers
C.
Flavor enhancers
D.
Coloring agents
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Solution
Emulsifiers help to stabilize mixtures of oil and water in food products.
Correct Answer: B — Stabilizers
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Q. What is the role of enzymes in biochemical reactions?
A.
Increase activation energy
B.
Decrease activation energy
C.
Change the equilibrium of the reaction
D.
Provide energy for the reaction
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Solution
Enzymes act as catalysts that decrease the activation energy required for biochemical reactions.
Correct Answer: B — Decrease activation energy
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Q. What is the role of enzymes in biological systems?
A.
To provide structural support
B.
To act as catalysts for biochemical reactions
C.
To store genetic information
D.
To transport molecules across membranes
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Solution
Enzymes are proteins that act as catalysts, speeding up biochemical reactions without being consumed in the process.
Correct Answer: B — To act as catalysts for biochemical reactions
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Q. What is the role of histamines in the body?
A.
To promote sleep
B.
To regulate blood sugar
C.
To trigger allergic reactions
D.
To enhance digestion
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Solution
Histamines are chemicals that play a key role in allergic reactions.
Correct Answer: C — To trigger allergic reactions
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Q. What is the role of RNA in protein synthesis?
A.
Storage of genetic information
B.
Transcription of DNA
C.
Translation of proteins
D.
Both transcription and translation
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Solution
RNA plays a crucial role in both the transcription of DNA and the translation of proteins.
Correct Answer: D — Both transcription and translation
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Q. What is the role of temperature in the behavior of semiconductors?
A.
It has no effect
B.
It decreases conductivity
C.
It increases the number of charge carriers
D.
It only affects p-type semiconductors
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Solution
Temperature increases the number of charge carriers in semiconductors, thus increasing their conductivity.
Correct Answer: C — It increases the number of charge carriers
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Q. What is the role of the cathode in an electrochemical cell?
A.
Oxidation occurs
B.
Reduction occurs
C.
Electrons are lost
D.
Ions are produced
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Solution
In an electrochemical cell, reduction occurs at the cathode.
Correct Answer: B — Reduction occurs
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Q. What is the role of the coherent sources in an interference experiment?
A.
To provide different wavelengths
B.
To ensure constant phase difference
C.
To increase the amplitude
D.
To decrease the wavelength
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Solution
Coherent sources maintain a constant phase difference, which is essential for producing a stable interference pattern.
Correct Answer: B — To ensure constant phase difference
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Q. What is the role of the galvanometer in a potentiometer circuit?
A.
To measure current
B.
To measure resistance
C.
To indicate the balance point
D.
To provide a reference voltage
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Solution
The galvanometer indicates the balance point in a potentiometer circuit, showing when the potential difference across the wire equals the unknown voltage.
Correct Answer: C — To indicate the balance point
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Q. What is the role of the galvanometer in a Wheatstone bridge?
A.
To measure voltage
B.
To measure current
C.
To detect balance
D.
To provide power
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Solution
The galvanometer is used to detect whether the bridge is balanced or unbalanced.
Correct Answer: C — To detect balance
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Q. What is the role of the jockey in a potentiometer setup?
A.
To connect the circuit
B.
To measure current
C.
To find the balance point
D.
To provide a fixed voltage
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Solution
The jockey is used to find the balance point in the potentiometer setup by sliding along the wire.
Correct Answer: C — To find the balance point
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Q. What is the role of the jockey in a potentiometer?
A.
To measure current
B.
To connect the circuit
C.
To find the null point
D.
To provide a reference voltage
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Solution
The jockey is used to find the null point where the potential difference is balanced, indicating the measurement of the unknown voltage.
Correct Answer: C — To find the null point
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Q. What is the role of the phase change upon reflection in thin film interference?
A.
It enhances constructive interference
B.
It enhances destructive interference
C.
It has no effect
D.
It changes the wavelength
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Solution
A phase change of π (or half a wavelength) occurs upon reflection from a medium of higher refractive index, affecting the interference pattern.
Correct Answer: B — It enhances destructive interference
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Q. What is the role of the refractive index in thin film interference?
A.
It determines the wavelength of light
B.
It affects the phase change upon reflection
C.
It has no effect
D.
It only affects the intensity
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Solution
The refractive index affects the phase change upon reflection; a higher refractive index can lead to a phase change of π (180 degrees).
Correct Answer: B — It affects the phase change upon reflection
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