IIT JEE Practice Question and Answer

Q: Chennai express left Hyderabad for Chennai at 14 : 30 hours, travelling at a speed of 60 kmph and Charminar Express left Hyderabad for Chennai on the same day at 16 : 30 hours, travelling at a speed of 80 kmph. How far away from Hyderabad will the two trains meet? 1809 0

  • 1
    360 kms
    Correct
    Wrong
  • 2
    480 kms
    Correct
    Wrong
  • 3
    520 kms
    Correct
    Wrong
  • 4
    240 kms
    Correct
    Wrong
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Answer : 2. "480 kms"
Explanation :

Answer: B) 480 kms Explanation: Now, the distance covered by Chennai express in 2 hrs = 60 x 2 = 120 kms Let the Charminar Express takes 't' hrs to catch Chennai express => 80 x t = 60 x (2 + t) => 80 t = 120 + 60t => t = 6 hrs   Therefore, the distance away from Hyderabad the two trains meet = 80 x 6 = 480 kms.

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Answer : 3. "80%"
Explanation :

Answer: C) 80% Explanation: circumference of A = 2πr = 8 => so r = 4πvolume = π×4π2×10 = 160πcircumference of B = 2πr   = 10 => so r = 5πvolume = π×5π2×8 =  200πso ratio of capacities = 160/200 = 0.8 so capacity of A will be 80% of the capacity of B.

Q: Which of the following is an Autotroph? 1808 0

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    Fish
    Correct
    Wrong
  • 2
    Algae
    Correct
    Wrong
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    Butterfly
    Correct
    Wrong
  • 4
    Mushroom
    Correct
    Wrong
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Answer : 2. "Algae"
Explanation :

Answer: B) Algae Explanation: Here from the above options, Algae is an Autotroph. Autotrophs :  An Autotroph is also called as Producer, is an organism that produces complex organic compounds from simple substances present in its surroundings, generally using energy from light or inorganic chemical reactions.

Q: Which of the Following is an Amorphous solid? 1808 0

  • 1
    Quartz Glass(Sio2)
    Correct
    Wrong
  • 2
    Chrome Alum
    Correct
    Wrong
  • 3
    Silicon Carbide(SiC)
    Correct
    Wrong
  • 4
    Graphite
    Correct
    Wrong
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Answer : 1. "Quartz Glass(Sio2)"
Explanation :

Answer: A) Quartz Glass(Sio2) Explanation: An amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In Brief, An amorphous solid is any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel. Quartz glass (SiO2) is an amorphous solid due to its short range order of constituent particles. Note Quartz is a crystalline solid while quartz glass is an amorphous solid.

Q: The sum of the digits of a two-digits number is 10,while when the digits are reversed, the number decreases by 54. Find the changed number ? 1808 0

  • 1
    28
    Correct
    Wrong
  • 2
    19
    Correct
    Wrong
  • 3
    37
    Correct
    Wrong
  • 4
    46
    Correct
    Wrong
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Answer : 1. "28"
Explanation :

Answer: A) 28 Explanation: Let the original number is 82 i.e 8 + 2 = 10 and when the digits are reversed i.e 28The difference is 82 - 28 = 54 i.e, the number is decreased by 54.

Q: There are 15 lines in plane. How many intersections (Maximum) can be made ? 1807 0

  • 1
    55
    Correct
    Wrong
  • 2
    105
    Correct
    Wrong
  • 3
    215
    Correct
    Wrong
  • 4
    148
    Correct
    Wrong
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Answer : 2. "105"
Explanation :

Answer: B) 105 Explanation: First line will cut all other 14, similarly second will cut 13, and so onTotal = 14+13+12+11+10+9+8+7+6+5+4+3+2+1 = 105.

Q: How long will it take for two pipes A and B to fill an empty cistern if they worked alternately for an hour each ? A. Working alone, Pipe A can fill the cistern in 40 hoursB. Pipe B is one third as efficient as Pipe A 1807 0

  • 1
    Only A is sufficient
    Correct
    Wrong
  • 2
    Only B is sufficient
    Correct
    Wrong
  • 3
    Both (A) and (B) are sufficient
    Correct
    Wrong
  • 4
    A) and (B) are sufficient D)
    Correct
    Wrong
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Answer : 3. "Both (A) and (B) are sufficient"
Explanation :

Answer: C) Both (A) and (B) are sufficient Explanation: From statement A, we know that Pipe A can fill the tank in 40 hours. However, this information is not sufficient as we do not have the data for Pipe B. Hence, statement A alone cannot answer the given question.From statement B, we know that Pipe B is one third as efficient as pipe A. However, we do not know the rate at which Pipe A fills the tank. Hence, we will not be able to find the rate at which Pipe B fills the cistern. Therefore, statement B alone is not sufficient to answer the question.Now, if we combine the two statements, we know that Pipe A take 40 hours to fill the cistern.Pipe B takes 120 hours to fill the cistern.If they worked alternately, then either Pipe A could have started the cycle or Pipe B could have started the cycle.If Pipe A started the sequence of filling alternately, then at the end of two hours, the two pipes together would have filled 1/40 + 1/120 = 1/30  th of the tank in an hour. Or the cistern will fill in 30 hours.If Pipe B started the sequence, then at the end of 2 hours, the two pipes together would have filled 1/120 + 1/40 = 1/30 th of the tank in an hour. Or the cistern will fill in 30 hours.As the answer obtained irrespective of which pipe started the sequence is the same, the correct answer is (3) - i.e., both the statement are sufficient to answer the question.

Q: Math Challenge 1807 0

  • 1
    7
    Correct
    Wrong
  • 2
    44
    Correct
    Wrong
  • 3
    4
    Correct
    Wrong
  • 4
    33
    Correct
    Wrong
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Answer : 3. "4"
Explanation :

Answer: C) 4 Explanation: Let the required number be 'N' given that its quarter i.e; N/4 exceeds its double i.e, 2N by 7 => N/4 + 7 = 2N => N + 28 = 8N 7N = 28 N = 4.

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