IIT JEE Practice Question and Answer

Q: What happens during the S-phase of the cell cycle? 1814 0

  • 1
    cell division
    Correct
    Wrong
  • 2
    cell growth
    Correct
    Wrong
  • 3
    DNA replication
    Correct
    Wrong
  • 4
    protein and enzyme synthesis
    Correct
    Wrong
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Answer : 3. "DNA replication"
Explanation :

Answer: C) DNA replication Explanation: S-phase (synthesis phase) is the part of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Precise and accurate DNA replication is necessary to prevent genetic abnormalities which often lead to cell death or disease.

Q: Which of these molecules are polar? Check all that apply. 1814 0

  • 1
    SO2
    Correct
    Wrong
  • 2
    CH2Cl2
    Correct
    Wrong
  • 3
    PCl3
    Correct
    Wrong
  • 4
    All the above
    Correct
    Wrong
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Answer : 4. "All the above"
Explanation :

Answer: D) All the above Explanation:    1) SO2                  2) CH2Cl2                3) PCl3 How to check the given molecules are polar or non polar : If the electronegativity of the two bonded atoms are different then the bond is polar. Although, some molecules contain polar bonds, the molecule may be non-polar. If the polarity of all the bonds present in the molecule are cancel each other then molecule is non-polar.   In the given options, SO2  is polar because the dipole moments on the O do not cancel. PCl3  is polar because the P-Cl bonds do not cancel out. CH2Cl2  polar because the C-Cl bonds do not cancel.   Hence, in brief, Polar molecules are molecules with net dipole due to the presence of partial positive and partial negative charge. For example, water is a polar molecule that has partial positive and partial negative charge on it. CO2 is a non polar compound.   Therefore, all the given options SO2, CH2Cl2 and PCl3 are Polar molecules.

Q: Acceptable noise level for human ear 1814 0

  • 1
    > 85 db
    Correct
    Wrong
  • 2
    = 85 db
    Correct
    Wrong
  • 3
    < 85 db
    Correct
    Wrong
  • 4
    None of the above
    Correct
    Wrong
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Answer : 3. "< 85 db"
Explanation :

Answer: C) < 85 db Explanation: Sound intensity or level is measured by a unit called a decibel. An 85 decibel noise level is not a safe standard for the public.   Hence, Acceptable noise level for human ear is less than 85 db.

Q: When Was The Tripitaka Written 1814 0

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Answer :
Explanation :

The Tripitaka was Written in Third Century bce(beginning of the common era). The Tripitaka (called Tipitaka in Pali) is the earliest collection of buddhist writings. Initially, they were composed orally.

Q: Choose the synonym of 'Hypothesis' from the following options ? 1814 0

  • 1
    Theory
    Correct
    Wrong
  • 2
    Fascination
    Correct
    Wrong
  • 3
    Complexity
    Correct
    Wrong
  • 4
    Falling
    Correct
    Wrong
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Answer : 1. "Theory"
Explanation :

Answer: A) Theory Explanation: 'Hypothesis' is a word that gives a brief explanation of the concepts based on the limited evidence. The word 'theory' is closest in meaning to it.

Q: Which compound matches the IR Spectrum? 1813 0

  • 1
    1, 5 – hexadiene
    Correct
    Wrong
  • 2
    3 – Hexanol
    Correct
    Wrong
  • 3
    Trans – 4 – octene
    Correct
    Wrong
  • 4
    None of the above
    Correct
    Wrong
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Answer : 1. "1, 5 – hexadiene"
Explanation :

Answer: A) 1, 5 – hexadiene Explanation: 3 – Hexanol: There is no alcohol stretch present in the spectrum. Therefore, the above structure is not suitable for the given spectrum.   Trans – 4 – octene: There is no vinyl bending present in the spectrum. Therefore, the above structure is not suitable for the given spectrum. 1, 5 – hexadiene: The vinyl bending and other stretches were matched with the above structure.     Hence, the c = c stretch, vinyl bending and stretch were matched with the above structure. Therefore, the given spectrum belongs to 1, 5 – hexadiene.

Q: Which of the following is the longest river in India? 1813 0

  • 1
    Godavari
    Correct
    Wrong
  • 2
    Ganga
    Correct
    Wrong
  • 3
    Yamuna
    Correct
    Wrong
  • 4
    Brahmaputra
    Correct
    Wrong
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Answer : 2. "Ganga"
Explanation :

Answer: B) Ganga Explanation: India is a land of rivers. Rivers are generally treated as mothers and almost every major river of India has a legend regarding its origin.   The Ganges or Ganga is the longest river of India, if we consider the total distance covered by a river within India. Two major rivers of the Indian subcontinent – Brahmaputra and Indus – are though longer than the Ganges, but the distances these two rivers cover within India are much shorter than that of the Ganges. The Ganges is the most sacred river to the Hindus. The Ganges originates from Gangotri Glacier (Uttarakhand). The total length that the Ganges covers during its journey is 2,525 kilometers (1569 miles) before it discharges in the Bay of Bengal.   The Godavari, also known as 'Dakshin Ganga' – the South Ganges, is the second longest river of India. It originates from Triambakeshwar, Nasik (Maharashtra), and travels through Chhattisgarh, Telangana and Andhra Pradesh, before discharging into Bay of Bengal.

Q: Thrice the square of a natural number decreased by 4 times the number is equal to 50 more than the number. The number is  ? 1812 0

  • 1
    5
    Correct
    Wrong
  • 2
    4
    Correct
    Wrong
  • 3
    7
    Correct
    Wrong
  • 4
    6
    Correct
    Wrong
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Answer : 1. "5"
Explanation :

Answer: A) 5 Explanation: Let the number be x. Then,   3x2 - 4x = x + 50   3x2- 5x - 50 = 0   (3x + 10)(x - 5) = 0   x = 5

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