IIT JEE Practice Question and Answer

Q: Why is burning coal a major source of pollution? 1411 0

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Answer :
Explanation :

Coal is chemically complex fuel. Whenever it is burned, gases are given off and particles of ash, called "fly ash," are released. Release of sulfur from burning into the air. The sulfur in coal combines with oxygen to form sulfur dioxide, which can be a major source of air pollution if emitted in large enough quantities. This stuff comes back as acid rain when it attaches itself to a raindrop.    Today, many of the effects of coal burning have been reduced significantly or eliminated. This is super-nasty and is only stopped by buying low-sulfur coal from Montana or Wyoming. The eastern power plants have to pay to move the coal from out west and this increases the price of power production.

Q: If in the following set of numbers, the first and the third digits are interchanged in each number, which number will be second from the end if arranged in ascending order after interchanging the digits ? 585  546  514  404  206  369 1410 0

  • 1
    404
    Correct
    Wrong
  • 2
    585
    Correct
    Wrong
  • 3
    415
    Correct
    Wrong
  • 4
    602
    Correct
    Wrong
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Answer : 3. "415"
Explanation :

Answer: C) 415 Explanation: Given numbers are 585 546 514 404 206 369Then interchanging the 1st and 3rd digits of the given numbers, we get585 645 415 404 602 963Now, arranging them in ascending order963 645 602 585 415 404Then the last second number is 415.

Q: Intermolecular forces in HCl are 1410 0

  • 1
    Hydrogen bonding
    Correct
    Wrong
  • 2
    Dipole-dipole
    Correct
    Wrong
  • 3
    Dispersion force
    Correct
    Wrong
  • 4
    All the above
    Correct
    Wrong
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Answer : 4. "All the above"
Explanation :

Answer: D) All the above Explanation: Intermolecular forces : The forces of attraction present in between the molecules or atoms or compounds is termed as intermolecular forces. The molecule HCl is composed of hydrogen and chlorine atom. There is high difference in electronegativities therefore, it is polar in nature. The H end of HCl is permanently slightly positive charge. The Cl end of HCl has a permanent slight negative charge. the "H" in one molecule is attracted to the "Cl" in a neighbor. The intermolecular force is weak compared to a covalent bond. But this dipole-dipole interaction is one of the stronger intermolecular attractions. It also has hydrogen bonding and dispersion forces.  Dispersion forces are the weakest forces which are present in between all molecules or atoms.Hydrogen bonds are present in molecules having at least one H-A bond where A is the strong electronegative atom (mainly F, Cl and N).

Q: I am always infront of you, but you will never see me. Who am I? 1409 0

  • 1
    Mirror
    Correct
    Wrong
  • 2
    Shadow
    Correct
    Wrong
  • 3
    Future
    Correct
    Wrong
  • 4
    None of the above
    Correct
    Wrong
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Answer : 3. "Future"
Explanation :

Answer: C) Future Explanation: Yes, future is always infront of us, but no one can see it.

Q: 125% as a Fraction? 1409 0

  • 1
    1/4
    Correct
    Wrong
  • 2
    3/4
    Correct
    Wrong
  • 3
    5/4
    Correct
    Wrong
  • 4
    7/4
    Correct
    Wrong
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Answer : 3. "5/4"
Explanation :

Answer: C) 5/4 Explanation: Literally any percentage means divide by 100. So 125% = 125100. That can be reduced to 5/4. To convert to a decimal, you can do long division, dividing 5 into 4.

Q: The price of 2 oranges, 3 bananas and 4 apples is Rs. 15. The price of 3 oranges, 2 bananas and 1 apple is Rs. 10. What will be price of 4 oranges, 4 bananas and 4 apples  ? 1407 0

  • 1
    Rs. 10
    Correct
    Wrong
  • 2
    Rs. 15
    Correct
    Wrong
  • 3
    Rs. 20
    Correct
    Wrong
  • 4
    Rs. 25
    Correct
    Wrong
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Answer : 3. "Rs. 20"
Explanation :

Answer: C) Rs. 20 Explanation: Let the Oranges be 'O', Bananas be 'B' and Apples be 'A' From the given data,   2O + 3B + 4A = 15 ...... (I) 3O + 2B + A = 10 ..... (II) On adding (I) and (II), 5O + 5B + 5A = 25 O + B + A = 5 4O + 4B + 4A = 20.

Q: Consider 5 independent Bernoulli’s trials each with probability of success p. If the probability of at least one failure is greater than or equal to 31/32 , then p lies in the interval ? 1406 0

  • 1
    [1, 32]
    Correct
    Wrong
  • 2
    (0, 1)
    Correct
    Wrong
  • 3
    [1, 1/2]
    Correct
    Wrong
  • 4
    (1, 1/2]
    Correct
    Wrong
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Answer : 3. "[1, 1/2]"
Explanation :

Answer: C) [1, 1/2] Explanation: Probability of atleast one failure= 1 - no failure > 31/32= 1 - P5 > 31/32=  P5<1/32= p < 1/2Also p > 0Hence p lies in [0,1/2].

Q: Which of the following is a property of sodium hydroxide? 1406 0

  • 1
    It is insoluble in ether and other Non-polar solvents
    Correct
    Wrong
  • 2
    It is slowly soluble in water
    Correct
    Wrong
  • 3
    It has an odor of rotten egg smell
    Correct
    Wrong
  • 4
    All the above
    Correct
    Wrong
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Answer : 1. "It is insoluble in ether and other Non-polar solvents"
Explanation :

Answer: A) It is insoluble in ether and other Non-polar solvents Explanation: Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−. Properties: 1. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. 2. NaOH is insoluble in ether and other non-polar solvents. 3. It is an odorless compound.   Uses: Sodium hydroxide is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents, and as a drain cleaner.

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