IIT JEE Practice Question and Answer

Q: Which Color has the Longest Wavelength? 1109 0

  • 1
    Violet
    Correct
    Wrong
  • 2
    Yellow
    Correct
    Wrong
  • 3
    Red
    Correct
    Wrong
  • 4
    White
    Correct
    Wrong
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Answer : 3. "Red"
Explanation :

Answer: C) Red Explanation: The visible colors from Longest wavelength to Shortest wavelength are :: Red, Orange, Yellow, Green, Blue and Violet.                     Red > Orange > Yellow > Green > Blue > Violet.   1. Infrared radiation has a longer wavelength than visible Red light.   2. Ultraviolet radiation has a shorter wavelength than the visible violet light.    3. The white light is a mixture of the colors of the visible spectrum.

Q: Which compound forms a colored aqueous solution? 1103 0

  • 1
    CrCl3
    Correct
    Wrong
  • 2
    KBr
    Correct
    Wrong
  • 3
    CaCl2
    Correct
    Wrong
  • 4
    NaOH
    Correct
    Wrong
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Answer : 1. "CrCl3"
Explanation :

Answer: A) CrCl3 Explanation: Colored aqueous solutions are a characteristic of transition compounds. The only transition compound in the above choices is CrCl3. Cr is a transition element.

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Answer :
Explanation :

We can make an equation: 3(100000 + x) = 10x+1 (Why? Well, adding 100000 puts a 1 at the front of a five-digit number, and multiplying by 10 and adding 1 puts a 1 at the end of a number) Solving this gives: 10x+1 = 3(100000 + x) 10x+1 = 300000 + 3x 10x = 299999 + 3x7x = 299999x = 299999/7 = 42857 The answer is 42857 (142857 is three times smaller than 428571).

Q: Which of the following is a Composite number? 1088 0

  • 1
    0
    Correct
    Wrong
  • 2
    19
    Correct
    Wrong
  • 3
    29
    Correct
    Wrong
  • 4
    91
    Correct
    Wrong
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Answer : 4. "91"
Explanation :

Answer: D) 91 Explanation: Here in the given numbers 91 is a Composite number. Since it has factors of 7 and 13 other than 1 and itself.   Composite Numbers : A composite number is a positive integer which is not prime (i.e., which has factors other than 1 and itself). Examples :: 4, 6, 8, 12, 14, 15, 18, 20, ...

Q: Present ages of Deepa and Hyma are in the ratio of 5:6 respectively. After four years, this ratio becomes 6: 7. What is the difference between their present ages? 1078 0

  • 1
    6 yrs
    Correct
    Wrong
  • 2
    4 yrs
    Correct
    Wrong
  • 3
    8 yrs
    Correct
    Wrong
  • 4
    2 yrs
    Correct
    Wrong
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Answer : 2. "4 yrs"
Explanation :

Answer: B) 4 yrs Explanation: Let the present age of Deepa = 5p Let the present age of Hyma = 6p After four years their ratio = 6 : 7 => 5p + 46p + 4 = 67 => 35p + 28 = 36p + 24 => p = 4 Therefore, the difference between their ages = 24 - 20 = 4 years.

Q: A person can row 8 1/2 km an hour in still water and he finds that it takes him twice as long to row up as to row down the river. The speed of the stream ? 1077 0

  • 1
    1.78 kmph
    Correct
    Wrong
  • 2
    2.35 kmph
    Correct
    Wrong
  • 3
    2.83 kmph
    Correct
    Wrong
  • 4
    3.15 kmph
    Correct
    Wrong
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Answer : 3. "2.83 kmph"
Explanation :

Answer: C) 2.83 kmph Explanation: Given speed of the person = 8 1/2 = 17/2 kmphLet the speed of the stream = x kmphspeed of upstream = 17/2 - xspeed of downstream = 17/2 + xBut given that,2(17/2 - x) = 17/2 + x=> 3x = 17/2=> x = 2.83 kmph.

Q: Who is the author of the book "The Hungry Tide"? 1073 0

  • 1
    Mitali Meelan
    Correct
    Wrong
  • 2
    Ravinder Singh
    Correct
    Wrong
  • 3
    Amitav Ghosh
    Correct
    Wrong
  • 4
    Sudha Murty
    Correct
    Wrong
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Answer : 3. "Amitav Ghosh"
Explanation :

Answer: C) Amitav Ghosh Explanation:

Q: Which sample is a pure substance? 1073 0

  • 1
    Table salt
    Correct
    Wrong
  • 2
    Pure water
    Correct
    Wrong
  • 3
    a test tube of zinc oxide
    Correct
    Wrong
  • 4
    All the above
    Correct
    Wrong
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Answer : 4. "All the above"
Explanation :

Answer: D) All the above Explanation: A pure substance can be defined as any single type of material that has not been contaminated by another substance. In chemistry, a pure substance has a definite composition. It can be a compound or an element. A pure substance is considered to be a material that consists of one type of "building block" of matter. Examples of pure substances include tin, sulfur, diamond, water, pure sugar (sucrose), table salt (sodium chloride) and baking soda (sodium bicarbonate). Tin, sulfur, and diamond are examples of pure substances which are chemical elements. All elements are pure substances. Water, sugar, salt and baking soda are pure substances which are chemical compounds. Chemical compounds also are pure substances

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