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 71: Which of the following statements supports the assumption that light travels in straight lines?
Options:
A) light can be diffracted
B) a source of light produces distinct shadows of opaque objects
C) a source of light produces interference patterns on a suitably placed screen
D) light can be reflected
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The correct answer is B .
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Question 72: How many grams of water at 17oC must be added to 42g of ice at 0oC to melt the ice completely? [specific latent heat of fusion of ice = 3.4 x 105Jkg-1, specific heat capacity of water = 4200Jkg-1k-1]
Options:
A) 200g
B) 300g
C) 320g
D) 400g
Show Answer
The correct answer is A .
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Question 73:
A machine gun with a mass of 5kg fires a 50g bullet at a speed of 100 ms. The recoil speed of the machine gun is
Options:
A) 0.5 ms
B) 1.5 ms
C) 1 ms
D) 2ms
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The correct answer is C .
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Question 74: A certain radioisotope of emits four alpha particles and three beta particles. The mass number and the atomic number of the resulting elements respectively are
Options:
A) 219 and 87
B) 84 and 223
C) 223 and 87
D) 219 and 81
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The correct answer is A .
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Question 75: The energy contained in a wire when it extended by 0.02m by a force 500 N is
Options:
A) 5J
B) 10J
C) 103J
D) 104
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The correct answer is A .
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Question 76: Two metals P and Q of length l1 and l2 are heated through the same temperature difference. If the ratio of the linear expansivities of P to Q is 2:3 and the ratio of lengths is 3:4. What is the ratio of increase in length of P to Q?
Options:
A) 7:5
B) 5:7
C) 1:2
D) 2:1
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The correct answer is C .
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Question 77: The battery connection that permits current to flow across a p-n junction is called?
Options:
A) reverse baised
B) forward baised
C) amplification.
D) rectification
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The correct answer is B .
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Question 78:
Two bodies have masses in the ratio3:1. They experience forces whichimpart to them,acceleration in the ratio 2:9 respectively. Find the ratio of forces the masses experienced
Options:
A) 1:4
B) 2:1
C) 2:3
D) 2:5
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The correct answer is C .
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Question 79:
The potential energy in an elastic string of force constant k, which has an extension X is?
Options:
A) kX
B) KX
C) ½KX
D) ½K
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The correct answer is C .
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Question 80: What happens when a, certain quantity of pure ice is completely changed to water at 0oC?
Options:
A) latent heat is absorbed, the mass remains constant, and the volume decreases
B) latent heat is given out, the mass remains constant and the volume decreases
C) latent heat is given out, the mass increases and the volume remains constant
D) latent heat is absorbed, the mass decreases and the volume increases
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The correct answer is B .