Q. What is the primary purpose of a demodulator in a communication system?
A.
To amplify the signal
B.
To convert the signal back to its original form
C.
To filter the noise
D.
To encode the signal
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Solution
A demodulator converts the modulated signal back to its original form.
Correct Answer: B — To convert the signal back to its original form
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Q. What is the primary purpose of a modulator in a communication system?
A.
To amplify the signal
B.
To convert digital signals to analog
C.
To filter noise
D.
To encode information
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Solution
A modulator converts digital signals to analog for transmission.
Correct Answer: B — To convert digital signals to analog
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Q. What is the primary purpose of modulation in communication systems?
A.
To increase the bandwidth of the signal
B.
To reduce noise in the signal
C.
To allow the transmission of signals over long distances
D.
To convert digital signals to analog signals
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Solution
Modulation allows signals to be transmitted over long distances by shifting the frequency of the signal to a higher range, making it suitable for transmission through various media.
Correct Answer: C — To allow the transmission of signals over long distances
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Q. What is the primary reaction occurring in a lead-acid battery during discharge?
A.
Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
B.
PbSO4 + 2H2O → Pb + PbO2 + 2H2SO4
C.
2Pb + 2H2SO4 → 2PbSO4 + H2
D.
PbO2 + 2H2SO4 → Pb + 2H2O + O2
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Solution
During discharge, the primary reaction in a lead-acid battery is Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O.
Correct Answer: A — Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
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Q. What is the primary reason for the +M effect of -OCH3?
A.
Inductive effect
B.
Resonance effect
C.
Steric hindrance
D.
Electronegativity
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Solution
The +M effect of -OCH3 is primarily due to resonance effect, where the lone pairs on oxygen can delocalize into the aromatic ring.
Correct Answer: B — Resonance effect
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Q. What is the primary reason for the acidity of chloroacetic acid compared to acetic acid?
A.
Inductive effect
B.
Mesomeric effect
C.
Steric hindrance
D.
Hydrogen bonding
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Solution
The inductive effect of the -Cl group in chloroacetic acid increases its acidity compared to acetic acid.
Correct Answer: A — Inductive effect
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Q. What is the primary reason for the color of transition metal complexes?
A.
Presence of unpaired electrons
B.
Crystal field splitting
C.
Ligand field theory
D.
All of the above
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Solution
The color of transition metal complexes arises from the presence of unpaired electrons and the crystal field splitting of d-orbitals.
Correct Answer: D — All of the above
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Q. What is the primary reason for the color of transition metal compounds?
A.
Presence of unpaired electrons
B.
Ionic bonding
C.
Covalent bonding
D.
High electronegativity
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Solution
The color of transition metal compounds arises from the presence of unpaired electrons and d-d transitions.
Correct Answer: A — Presence of unpaired electrons
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Q. What is the primary reason for the compressibility of gases?
A.
High density
B.
Low temperature
C.
Large intermolecular spaces
D.
Strong intermolecular forces
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Solution
Gases are highly compressible due to large intermolecular spaces between particles.
Correct Answer: C — Large intermolecular spaces
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Q. What is the primary reason for the elevation of boiling point in a solution?
A.
Increased molecular weight
B.
Decreased vapor pressure
C.
Increased solubility
D.
Decreased temperature
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Solution
The elevation of boiling point occurs because the presence of solute lowers the vapor pressure of the solvent, requiring a higher temperature to reach boiling.
Correct Answer: B — Decreased vapor pressure
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Q. What is the primary reason for the formation of a precipitate in a saturated solution?
A.
Excess solute
B.
Temperature increase
C.
Change in pH
D.
Decrease in solubility product
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Solution
A precipitate forms when the ionic product exceeds the solubility product (Ksp) of the salt.
Correct Answer: D — Decrease in solubility product
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Q. What is the primary reason for the formation of droplets of water on a leaf?
A.
Cohesion
B.
Adhesion
C.
Surface tension
D.
Gravity
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Solution
The formation of droplets is primarily due to surface tension, which minimizes the surface area of the liquid.
Correct Answer: C — Surface tension
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Q. What is the primary reason for the high boiling point of water compared to other similar-sized molecules?
A.
Hydrogen bonding
B.
Van der Waals forces
C.
Ionic bonding
D.
Covalent bonding
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Solution
The high boiling point of water is primarily due to hydrogen bonding between water molecules.
Correct Answer: A — Hydrogen bonding
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Q. What is the primary reason for the high reactivity of alkali metals?
A.
High electronegativity
B.
Low ionization energy
C.
High atomic radius
D.
Presence of d-orbitals
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Solution
Alkali metals have low ionization energy, which contributes to their high reactivity.
Correct Answer: B — Low ionization energy
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Q. What is the primary reason for the high reactivity of halogens?
A.
Low electronegativity
B.
High ionization energy
C.
Desire to gain one electron
D.
Large atomic size
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Solution
Halogens are highly reactive because they have a strong desire to gain one electron to achieve a stable octet.
Correct Answer: C — Desire to gain one electron
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Q. What is the primary reason for the increase in pH when a weak acid is titrated with a strong base?
A.
Formation of water
B.
Neutralization of acid
C.
Formation of a conjugate base
D.
All of the above
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Solution
All of the above factors contribute to the increase in pH during the titration of a weak acid with a strong base.
Correct Answer: D — All of the above
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Q. What is the primary reason for the increase in viscosity of a liquid with molecular weight?
A.
Increased intermolecular forces
B.
Decreased temperature
C.
Increased pressure
D.
Decreased density
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Solution
Higher molecular weight leads to increased intermolecular forces, resulting in higher viscosity.
Correct Answer: A — Increased intermolecular forces
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Q. What is the primary reason for the increasing reactivity of alkali metals down the group?
A.
Increasing atomic size
B.
Decreasing ionization energy
C.
Increasing electronegativity
D.
Increasing metallic character
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Solution
The reactivity of alkali metals increases down the group due to decreasing ionization energy.
Correct Answer: B — Decreasing ionization energy
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Q. What is the primary reason for the lowering of vapor pressure in a solution?
A.
Increased temperature
B.
Decreased surface area
C.
Presence of solute particles
D.
Increased molecular weight of solvent
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Solution
The presence of solute particles reduces the number of solvent molecules at the surface, leading to a lower vapor pressure.
Correct Answer: C — Presence of solute particles
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Q. What is the primary reason for the occurrence of diffraction in waves?
A.
Wave interference
B.
Wave reflection
C.
Wave refraction
D.
Wave nature of light
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Solution
Diffraction occurs due to the wave nature of light, allowing it to bend around obstacles and spread out.
Correct Answer: D — Wave nature of light
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Q. What is the primary reason for the occurrence of diffraction?
A.
The wave nature of light
B.
The particle nature of light
C.
The speed of light
D.
The frequency of light
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Solution
Diffraction occurs due to the wave nature of light, allowing it to bend around obstacles.
Correct Answer: A — The wave nature of light
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Q. What is the primary reason for the operation of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Coulomb's law
D.
Ohm's law
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Solution
Electric motors operate based on the Lorentz force, which acts on current-carrying conductors in a magnetic field, causing rotation.
Correct Answer: B — Lorentz force
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Q. What is the primary reason for the phenomenon of capillarity?
A.
Surface tension
B.
Viscosity
C.
Density
D.
Pressure
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Solution
Capillarity is primarily caused by surface tension, which allows liquids to rise or fall in narrow spaces against gravity.
Correct Answer: A — Surface tension
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Q. What is the primary reason for the stability of benzene?
A.
Presence of double bonds
B.
Resonance stabilization
C.
High molecular weight
D.
Hydrogen bonding
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Solution
Benzene's stability arises from resonance stabilization, where the electrons are delocalized over the entire ring structure.
Correct Answer: B — Resonance stabilization
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Q. What is the primary reason for the stability of phenol compared to cyclohexanol?
A.
Inductive effect
B.
Mesomeric effect
C.
Steric hindrance
D.
Hydrogen bonding
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Solution
Phenol is stabilized by resonance (mesomeric effect) which is not present in cyclohexanol.
Correct Answer: B — Mesomeric effect
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Q. What is the primary reason for using insulation in buildings?
A.
To prevent conduction
B.
To enhance convection
C.
To increase radiation
D.
To allow heat flow
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Solution
Insulation is used primarily to prevent conduction of heat, thereby maintaining the desired temperature inside buildings.
Correct Answer: A — To prevent conduction
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Q. What is the primary reason gases can be compressed much more than liquids or solids?
A.
High density
B.
Low density
C.
Large intermolecular spaces
D.
Strong intermolecular forces
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Solution
Gases can be compressed due to large intermolecular spaces between particles, unlike liquids and solids.
Correct Answer: C — Large intermolecular spaces
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Q. What is the primary species present in a solution of acetic acid (CH3COOH)?
A.
CH3COO-
B.
H+
C.
CH3COOH
D.
H2O
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Solution
In a solution of acetic acid, the primary species present is the undissociated acetic acid (CH3COOH), along with some dissociated ions.
Correct Answer: C — CH3COOH
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Q. What is the primary species present in a solution of sodium acetate (CH3COONa)?
A.
CH3COO-
B.
Na+
C.
H+
D.
OH-
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Solution
In a solution of sodium acetate, the acetate ion (CH3COO-) is the primary species that affects the pH.
Correct Answer: A — CH3COO-
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Q. What is the primary storage form of carbohydrates in animals?
A.
Starch
B.
Glycogen
C.
Cellulose
D.
Chitin
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Solution
Glycogen is the primary storage form of carbohydrates in animals.
Correct Answer: B — Glycogen
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