Physics is the science that studies the nature and properties of matter and energy. It covers topics like motion, heat, light, sound, electricity, magnetism, and the structure of atoms.
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Question 81: In alternating current circuit at resonance, the angel of lead or lag is
Options:
A) π°
B) (π)/2°
C) (π)/3°
D) 0°
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The correct answer is B .
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Question 82:

From the diagram above, the inductive reactance and the resistance R are respectively
Options:
A) 50Ω and 45Ω
B) 25Ω and 51Ω
C) 20Ω and 50Ω
D) 10Ω and 49Ω
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The correct answer is D .
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Question 83: Calculate the heat energy lost when 10g of boiling water changes to ice at 0°C. [Specific latent heat of ice 336Jg-1 . Specific heat capacity of water 4.2Jg-1 K-1]
Options:
A) 840J
B) 3360J
C) 3420J
D) 4200J
E) 7560J
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The correct answer is E .
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Question 84: The speed of light in air is 3 x 108ms-1. What is the speed in glass with a refractive index of 1.50?
Options:
A) 1.5 x 108ms-1
B) 3.0 x 108ms-1
C) 2.0 x 108ms-1
D) 6.0 x 108ms-1
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The correct answer is C .
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Question 85:
A radioactive isotope has a decay constant of 10-6s-1.
Calculate its half - life?
Options:
A) 5.93 x 106s
B) 6.93 x 107s
C) 6.93 x 109s
D) 5.93 x 107s
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The correct answer is B .
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Question 86:
The vapour pressure?
Options:
A) increases non-linearly with measuring temperature
B) increases linearly with increasing temperature
C) decreases linearly with increasing temperature
D) decreases non-linearly ith measuring temperature
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The correct answer is A .
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Question 87: A string is fastened tightly between two walls 24cm apart. The wavelength of the second overtone is
Options:
A) 24cm
B) 16cm
C) 12cm
D) 8cm
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The correct answer is B .
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Question 88: Three electric cells each of e.m.f 1.5V and internal resistance of 1.0 are connected in parallel across an external resistance of . Calculate the value of the current in the resistor
Options:
A) 0.5 A
B) 0.9A
C) 1.5A
D) 4.5A
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The correct answer is C .
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Question 89: When a certain a.c supply is connected to a lamp, it lights with the same brightness as it does with a 12 V d.c battery. Then r.m.s value of the a.c supply is?
Options:
A) 12.0 V
B) 3.5 V
C) 17.0 V
D) 8.5
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The correct answer is A .
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Question 90: Which of the following scientists postulated that moving particles exhibit wave properties?
Options:
A) Niels Bohr
B) Ernest Rutherford
C) Werner Heisenberg
D) Louis de Broglie
E) Erwin Schroedinger
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The correct answer is D .