IIT JEE प्रश्न और उत्तर का अभ्यास करें

प्र: An object that has kinetic energy must be 1869 0

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    At an elevated position
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    Falling
    सही
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    At rest
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  • 4
    Moving
    सही
    गलत
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उत्तर : 4. "Moving"
व्याख्या :

Answer: D) Moving Explanation: In physics, we know that the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Hence, An object that has kinetic energy must be in motion i.e, moving.

प्र: Order of basicity of amines in gaseous state? 1298 0

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    2'> 1'> 3' > NH3
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    3' > 2' > 1'> NH3
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    1' > 2' > 3'> NH3
    सही
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  • 4
    2'> 3'> 1' > NH3
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उत्तर : 2. "3' > 2' > 1'> NH3"
व्याख्या :

Answer: B) 3' > 2' > 1'> NH3 Explanation: The order of basicity in ammonia is different in gaseous phases vs. aqueous phases due to hydrogen bonding.   So in gaseous phases it's the well known: 3' > 2' > 1'> NH3. Just so we're on the same page, this is due to the inductive effect of electron donating alkyl groups--they destabilize the lone pair on nitrogen atom, making nitrogen more basic.   But in aqueous phase, the order is slightly different: 2'> 1'> 3' > NH3.

प्र: Soil erosion on hillslopes can be checked by 4408 0

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    Terrace cultivation
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    Contour ploughing
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    Afforestation
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  • 4
    Strip cropping
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उत्तर : 1. "Terrace cultivation"
व्याख्या :

Answer: A) Terrace cultivation Explanation: Hence, soil erosion on hillslopes can be checked by Terrace cultivation.

प्र: Myeloid stem cells give rise to all leukocytes. 1613 0

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    TRUE
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  • 2
    FALSE
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उत्तर : 2. "FALSE"
व्याख्या :

Answer: B) FALSE Explanation: Hemopoiesis begins in the red bone marrow, with hemopoietic stem cells that differentiate into myeloid and lymphoid lineages.   Myeloid stem cells give rise to all the other formed elements, including the erythrocytes; megakaryocytes that produce platelets; and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes: neutrophils, eosinophils, and basophils.

प्र: Is a square a rhombus? 2139 0

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    TRUE
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  • 2
    FALSE Answer & Explanation Answer:
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उत्तर : 1. "TRUE"
व्याख्या :

Answer: A) TRUE Explanation: Yes, a square is a rhombus. But a rhombus is not a square unless the interior angles are at right angles.   We know that, a square is a quadrilateral with all sides equal and all the interior angles are 90 deg i.e, at right angles.  Whereas a rhombus is also a quadrilateral with all sides equal but the interior angles are not at right angles. Hence, if the interior angles of a rhombus are all at right angles (90 deg), then it is square.

प्र: What two scientists established the structure of dna? 1689 0

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    Rosalind Franklin and Maurice Wilkins
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    James Watson and Francis Crick
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    Rosalind Franklin and Francis Crick
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  • 4
    James Watson and Maurice Wilkins
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उत्तर : 2. "James Watson and Francis Crick"
व्याख्या :

Answer: B) James Watson and Francis Crick Explanation: In the early 1950s two scientists, Rosalind Franklin and Maurice Wilkins, studied DNA using x-rays. Franklin produced an x-ray photograph that allowed two other researchers, James Watson and Francis Crick to work out the 3D structure of DNA. The structure of DNA was found to be a double helix.

प्र: Rajesh rows in still water with a speed of 4.5 kmph to go to a certain place and comes back. Find his average speed for the whole journey, if the river is flowing with a speed of 1.5 kmph? 2509 0

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    2 kmph
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  • 2
    4 kmph
    सही
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  • 3
    6 kmph
    सही
    गलत
  • 4
    8 kmph
    सही
    गलत
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उत्तर : 2. "4 kmph"
व्याख्या :

Answer: B) 4 kmph Explanation: Let the distance in one direction = k kms Speed in still water = 4.5 kmph Speed of river = 1.5 Hence, speed in upstream = 4.5 - 1.5 = 3 kmph Speed in downstream = 4.5 + 1.5 = 6 kmph Time taken by Rajesh to row upwards = k/3 hrs Time taken by Rajesh to row downwards = k/6 hrs Now, required Average speed =Total distanceTotal speed = 2kk3 + k6 = 2k x 186k + 3k = 4 kmph    Therefore, the average speed of the whole journey = 4kmph.

प्र: What tastes better than it smells? 1151 0

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उत्तर :
व्याख्या :

Tongue. Yes tongue tastes better than it smells as it can't smell.

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