Ask questions which are clear, concise and easy to understand.

What wold have happened if mouth cavity and nasal passage were not separated? 

Posted by Rachna gupta (May 26, 2017 1:47 p.m.) (Question ID: 5502)

How does air in nasal passage disturbs food in mouth cavity?

Posted by Rachna gupta (May 26, 2017 1:42 p.m.) (Question ID: 5501)

Explain with the help of <i>diagram</i> where are stomata located on stems of herbaceous plants? 

Posted by Rachna gupta (May 25, 2017 4:11 p.m.) (Question ID: 5489)

  • Please reply.

    Please...

    Posted by Rachna gupta (May 25, 2017 6:55 p.m.)
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Explain with the help of a diagram where are stomata located on herbaceous plants.

Posted by Rachna gupta (May 25, 2017 2:04 p.m.) (Question ID: 5485)

  • Please reply. 

    Please...

    Posted by Rachna gupta (May 25, 2017 2:35 p.m.)
  • Please reply fast.

    Posted by Rachna gupta (May 25, 2017 2:13 p.m.)
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  • Answers:
  • Ans.In herbaceous plants stomata are commonly on both leaf surfaces, the upper (adaxial) and the lower (abaxial) surfaces.

    Answered by Naveen Sharma (May 25, 2017 3:07 p.m.)
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How does exchange of gases take place in herbaceous plants? Explain with diagram.

Posted by Rachna gupta (May 25, 2017 2:02 p.m.) (Question ID: 5484)

  • Please reply. 

    Please...

    Posted by Rachna gupta (May 25, 2017 2:36 p.m.)
  • PLEASE REPLY FAST.

    Posted by Rachna gupta (May 25, 2017 2:13 p.m.)
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  • Answers:
  • In plants, oxygen and carbon dioxide diffuse through the stomata and the intercellular spaces of the leaves, and the lenticels of the bark.

    Lenticels are small openings in the pits of the bark. The exchange of gases takes place through the lenticels also, apart from the exchange through the openings in the leaves.

    The direction of exchange of gases between a plant and its surroundings depends upon the time of the day and the usage of the gases by the plant. Plants respire throughout the day, while photosynthesis takes place only in the presence of sunlight. In daytime, carbon dioxide produced in respiration by the plants is used by them in photosynthesis. So, carbon dioxide is not released into the environment.

    In fact, plants take in additional carbon dioxide from the air for photosynthesis. Out of the oxygen produced in photosynthesis, some amount is consumed by the plants in respiration.

    The rest is released into the air through the stomata. At night, when there is no photosynthesis, no oxygen is released. Also, the carbon dioxide produced in respiration is not used by the plants. So, it is released in the air.

    Answered by Shivam .G (May 25, 2017 5:28 p.m.)
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During the process of respiration COand H2O are formed as by products. How do we eliminate water formed during the process.

Posted by Rachna gupta (May 24, 2017 11:19 p.m.) (Question ID: 5477)

  • Answers:
  • Along with carbondioxide, we also exhale water in the form of water vapour

    Proof -

    When we exhale on a lens in a pair of spectacles, we can clearly see a layer of water vapour on it.

    Answered by Ahmed Hamzah (May 25, 2017 12:11 a.m.)
    Thanks (2)
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Why bases does not react with metal carbonate or metal bicarbonate? 

 

Posted by Gagan Singh (May 24, 2017 8:49 p.m.) (Question ID: 5473)

  • Answers:
  • Metal Carbonates do not react with bases because metal carbonates are itself bases.

    So base when added to base gives no reaction.

    Answered by Payal Singh (May 24, 2017 8:51 p.m.)
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Why is some food left undigested?

Posted by Rachna gupta (May 24, 2017 2:27 p.m.) (Question ID: 5469)

  • Answers:
  • During digestion of food by products are formed that we can not digest.

    Answered by Rachna gupta (May 25, 2017 2:37 p.m.)
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Why can't our body digests certain types of food?

Posted by Rachna gupta (May 24, 2017 2:26 p.m.) (Question ID: 5468)

  • Answers:
  • Humans cannot digest certain types of food because the appropriate enzymes to breakdown the molecules, are lacking in our body.

    Answered by Payal Singh (May 24, 2017 2:36 p.m.)
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Why do we produce saliva when we see  food?

Posted by Rachna gupta (May 24, 2017 2:25 p.m.) (Question ID: 5467)

  • The process of digestion starts in our mouth when we start chewing food(in most cases). Most of the saliva helps breakdown all the starch and other compounds to sugars.

    So whenever you see and smell some delicious food your brain perceives you will eat it and hence asks the salivary glands to release the saliva in advance which we call mouth-watering.

    Posted by Payal Singh (May 24, 2017 3:48 p.m.)
  • But why is saliva produced when we see food?

    Posted by Rachna gupta (May 24, 2017 3:39 p.m.)
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  • Answers:
  • The process of digestion starts in our mouth when we start chewing food(in most cases). Most of the saliva helps breakdown all the starch and other compounds to sugars. So whenever you see and smell some delicious food your brain perceives you will eat it and hence asks the salivary glands to release the saliva in advance which we call mouth-watering.

    Answered by Payal Singh (May 24, 2017 3:46 p.m.)
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How come alimentary canal ( 9 metres ) can be longer than humans?

Posted by Rachna gupta (May 24, 2017 2:23 p.m.) (Question ID: 5465)

  • Answers:
  • Alimentary canal is longer but fits in our body as it is of different shapes and sizes at different levels.

    Answered by Rachna gupta (May 25, 2017 2:38 p.m.)
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Voltmeter has high resistance so that:

1) it takes large current from the circuit

2) it takes a negligible current from the circuit

3) it can be connected in series

4) none of these

Posted by Sudhanshu Baranwal (May 24, 2017 10:36 a.m.) (Question ID: 5458)

  • Answers:
  • 2) it takes a negligible current from the circuit

    Answered by Payal Singh (May 24, 2017 11:18 a.m.)
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A 500 gm packet having volume 300 cm3 is placed in water  (density of water = 1gm/cm3).  The packet will:

1) float in water 

2) sink in water

3) displace 500 gm water

4) displace 500 cm3 water.

Posted by Sudhanshu Baranwal (May 24, 2017 10:33 a.m.) (Question ID: 5457)

  • Answers:
  • 2) sink in water

     

    Explanation : density of packet ={tex}Mass \over Volume {/tex}

    {tex}500\over 300 {/tex}= 1.66 gm/cm3

    It has higher density than water so it ll sink 

    Answered by Payal Singh (May 24, 2017 11:20 a.m.)
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What is osmosis? 

 

Posted by Shubham Kardile (May 24, 2017 9:32 a.m.) (Question ID: 5451)

  • Answers:
  • Osmosis is a process in which the water molecules move from high concentration region to a low concentration region through a semi-permeable membrane.

     

    Answered by Archith jayalal (May 24, 2017 7:30 p.m.)
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  • Osmosis is the process in which water molecules moves from the region of high concentration to a region of low concentration through a semi permeable membrane.

    Answered by Payal Singh (May 24, 2017 9:43 a.m.)
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An electric heater of resistance 8 Ohm draws 15Amp. from the service mains 2hrs. What will be the rate at which heat is developed in the heater ?

(If you feel some error in the question then please tell me because this is an NCERT question.) 

Posted by Pranzal Kumar Sinha (May 24, 2017 9:08 a.m.) (Question ID: 5450)

  •  I think your answer will come 1800W.

    Posted by Pranzal Kumar Sinha (May 24, 2017 9:33 a.m.)
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  • Answers:
  • Ans. Given 
    Resistance of heater R = 8 Ohm

    Current I = 15 A

    Time = 2 Hours = {tex}2\times 3600 = 7200 \ s{/tex}

    According to Joule's Law of Heating:

    Heat  Generated H = {tex}I^2 .R. T{/tex}

    Rate of Heat Generated =  {tex}H\over T{/tex} = {tex}{I^2.R.T\over T} = I^2.R{/tex}

    {tex}(15)^2\times 8 = 225\times 8 = 1800 \ J/s{/tex}

    Answered by Naveen Sharma (May 24, 2017 9:41 a.m.)
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How to find chemical reactants and products symbolically?

Posted by Murali Dharan (May 24, 2017 6:07 a.m.) (Question ID: 5449)

  • Answers:
  • 6CO+ 12H2O ----> C6H12O+ 6O2 + 6H2O

    REACTANTS: CARBON DIOXIDE - CO2

                             WATER - H2

    PRODUCTS: GLUCOSE - C6H12O6

                           OXYGEN - O2

                           WATER - H2O

    Answered by Rachna gupta (May 25, 2017 2:48 p.m.)
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Give me information about courseOf term1 or SA1

Posted by gaurav dhakad (May 23, 2017 9:38 p.m.) (Question ID: 5446)

  • Answers:
  • There will be no SA 1 this year. Syllabus for 1st exam will be decided by school. 

    Thank you.

    Sorry for replying late.

    Answered by Rachna gupta (May 25, 2017 2:50 p.m.)
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A wire's diameter is doubled. What will be the new resistance?

Posted by Pranzal Kumar Sinha (May 23, 2017 2:08 p.m.) (Question ID: 5445)

  • Answers:
  • Ans. 

    We know that 

    Resistance R = {tex}\rho {L\over A}{/tex}

    Where {tex}\rho{/tex} is resistivity of material

    L is length of wire

    A is area of Cross-section of wire

    Area A = {tex}\pi r^2{/tex}

    If we double the Diameter it means radius is also doubled 

    So now Area = {tex}\pi (2r)^2= 4\pi r^2{/tex} = 4A

    So  New Resistance R' = {tex}\rho {L\over 4A} = {R\over 4}{/tex}

    Means new resistance will be {tex}({1\over 4})^{th}{/tex} of old resistance .

     

    Answered by Naveen Sharma (May 23, 2017 2:55 p.m.)
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The value of tan 90' is not defined  . Why ?

Posted by pritam mall (May 23, 2017 8:26 a.m.) (Question ID: 5443)

  • Answers:
  • Tangent of an angle is equal to the perpendicular divided by the base, As the angle approaches 90 degree, the value of the perpendicular starts to rise at abnormally higher rate but the value of the base remains same.

    At 90 degree, there will be no triangle as the perpendicular and hypotenuse will never meet or meet at infinity and in that case perpendicular and the hypotenuse both wil be infinie..

    tan 90 will be infinite

    Answered by Payal Singh (May 23, 2017 8:35 a.m.)
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Resistors which are connected in series have different potential difference. Why ?

Posted by pritam mall (May 23, 2017 8:21 a.m.) (Question ID: 5441)

An acidic oxide is formed by the element: 

1) H

2) K

3) Ca

4) C

Posted by Sudhanshu Baranwal (May 23, 2017 8:16 a.m.) (Question ID: 5439)

  • Answers:
  • 4. C

    Explanation: Those oxides which form acidic solutions on reaction with water are called acidic oxides, (or sometimes acid anhydrides). The acidic oxides are the oxides of the non-metal elements.

    Answered by Payal Singh (May 23, 2017 8:21 a.m.)
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A white precipitate is obtained by adding common salt solution into a solution of:

1) AgNO3

2) KNO3

3) NH4NO3

4) Ba(NO3)2

Posted by Sudhanshu Baranwal (May 23, 2017 8:15 a.m.) (Question ID: 5438)

  • Answers:
  • 1) AgNO3

    Explanation:

    NaCl + AgNO3{tex}\to{/tex} NaNO+ AgCl

     

    Silver chloride is  (White precipitate)

    Answered by Payal Singh (May 23, 2017 8:28 a.m.)
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Why are copper and aluminum wires usually employed for electricity transmission?

Posted by Anurag Patel (May 20, 2017 2:33 p.m.) (Question ID: 5393)

  • Answers:
  • Copper and aluminium wires are usually employed for electricity transmission because

    • These are extremely good conductors
    • They have a low value of resistivity.
    • these are ductile and can be drawn in the form of fine wiree.
    • They are extremely flexible and do not degrade under electrical transmission as do other metals.
    • They are less expensive than the best conductors, silver and gold.
    Answered by Payal Singh (May 20, 2017 2:51 p.m.)
    Thanks (1)
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Why is hydrogen peroxide is kept in coloured bottles??

Posted by Chandan Pradhan (May 19, 2017 7:44 p.m.) (Question ID: 5384)

  • Answers:
  • Hydrogen peroxide is a highly reactive that can react with light or heat to produce water. To prevent it's reaction with light and heat to make water it is stored in coloured bottles so that light does'nt pass through it.

    Answered by Payal Singh (May 20, 2017 10:18 a.m.)
    Thanks (1)
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What is the difference between rusting and corrosion?

Posted by Chandan Pradhan (May 19, 2017 7:43 p.m.) (Question ID: 5383)

  • Answers:
    1. Corrosion is the disintegration of materials due to chemical or electrochemical reactions while rust is a type of corrosion.
    2. Corrosion is the disintegration of all types of metals as well as materials such as polymers and ceramics while rust is the corrosion of iron and its alloys.
    3. Corrosion is caused by a material’s reaction to chemicals while rust is caused by water or moisture and oxidation.
    Answered by Payal Singh (May 19, 2017 9:12 p.m.)
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Who were joggers?

 

 

 

Posted by Arti Sharma (May 19, 2017 11:16 a.m.) (Question ID: 5375)

  • Answers:
  • Ans. Jobber : 'Jobbers' were usually employed by the industrialists to recruit the right people for work from villages out of the various job seekers. A jobber often demanded money or gifts for his favour (that is for finding a job for someone).

    The main functions of a Jobber were :

    (i) Getting people from villages.
    (ii) Ensuring them jobs.
    (iii) Helping them to settle in the city and to provide them money in times of crisis.

    Answered by Naveen Sharma (May 19, 2017 11:39 a.m.)
    Thanks (1)
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What is parallel combination?

 

 

Posted by Arti Sharma (May 19, 2017 11:14 a.m.) (Question ID: 5374)

  • Answers:
  • Ans. Parallel combination : A parallel combination of resistors is a combination in which the resistors are arranged with their heads connected together, and their tails connected together.

    The current in a parallel combination breaks up, with some flowing along each parallel branch and re-combining when the branches meet again.

    Answered by Naveen Sharma (May 19, 2017 11:37 a.m.)
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What is the difference between emf and potential difference?

Posted by JD Shukla (May 17, 2017 10:26 p.m.) (Question ID: 5358)

  • Answers:
  • 1.Emf is the total voltage in the battery while the potential difference is the work done in moving a charge against the electric field between two specific points in the circuit.

    2.Emf is always greater than the potential difference.

    3.The concept of emf is applicable only to an electrical field while the potential difference is applicable to magnetic, gravitational, and electric fields.

    Answered by Payal Singh (May 17, 2017 11:25 p.m.)
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If non green plants are not autotrophs how do they obtain food?

Posted by Rachna gupta (May 16, 2017 5:09 p.m.) (Question ID: 5333)

  • Answers:
  • Non-Green or Heterotrophic plants cannot synthesise food on their own but depend on other organisms for their nutrition.

    Heterotrophic plants can be further classified into parasites, saprophytes and symbiotic plants.

    Answered by Payal Singh (May 16, 2017 6:30 p.m.)
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How many extra electrons are present on a body having 2 coulombs of negative charge?

Posted by Tanishq Kabir (May 16, 2017 1:18 p.m.) (Question ID: 5327)

  • Answers:
  • Ans. We know the charge on an Electron is {tex}1.6 \times 10^{-19} C{/tex}

    So e = {tex}1.6 \times 10^{-19} C{/tex}

    Total Charge Required q = 2 C

    Since , q = ne 

    where n is no of electrons.

    So, n = {tex}q\over e{/tex} = {tex}2\over 1.6 \times 10^{-19} {/tex}

    {tex}{2 \times 10^{19} \over 1.6 }{/tex} = {tex}1.25 \times 10^{19}{/tex}

    Answered by Naveen Sharma (May 17, 2017 9:50 a.m.)
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