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

To prepare a soap by cold process 

Posted by Raj Kumar (Mar 27, 2017 8:44 a.m.) (Question ID: 4543)

  • Answers:
    • Take 25 ml of coconut oil in a measuring cylinder and pour it into a 250 ml glass beaker.
    • Measure 30 ml of 20% NaOH solution in another measuring cylinder and add it into the beaker containing vegetable oil.
    • Vigorously stir the mixture using a glass rod.
    • Touch the beaker from outside.  It is observed that the beaker is warm.
    • Place the beaker on a wire gauze placed over a tripod stand.
    • Heat the beaker using a Bunsen burner till the mixture become a whitish paste.
    • Remove the beaker from the flame and allow it to cool.
    • Dip a red litmus paper in the suspension formed.
    • When dipped in the suspension, the red litmus paper changes its colour to blue.
    • Dip a blue litmus paper in the suspension.
    • The colour of blue litmus paper remains the same.
    • To the above suspension, add 15g of common salt and stir it well with a glass rod.
    • After adding common salt, soap in the suspension gets precipitated out as solid.
    • Take a filter funnel and place a filter paper in it and fix it in a stand.
    • Place a beaker below the funnel.
    • Pour the contents of the beaker into the funnel over a glass rod and filter the contents of the beaker.
    • After filtration, soap is left behind in the filter paper.
    • Transfer the soap into another filter paper using a spatula and dry it by pressing with another filter paper.
    • Then, cut it into desired shape with a knife.
    Answered by Shweta Gulati (Mar 27, 2017 9:29 p.m.)
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How many isomers are possible of pentane ?Are side chains also included in isomers?

Posted by arya kavita (Mar 26, 2017 8:39 p.m.) (Question ID: 4535)

  • I need it urgent plzzzz

    Posted by arya kavita (Mar 26, 2017 9:23 p.m.)
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  • Answers:
  • Ans. Three structural isomers are possible for pentane.

    Answered by Naveen Sharma (Mar 27, 2017 6:31 a.m.)
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A hypermetrophia person near point Is 75 cm he uses a lens of 100cm focal length find its farthest point 

Posted by Sai Kilani (Mar 26, 2017 12:29 p.m.) (Question ID: 4519)

  • Please answer it helps about 53 students 

     

     

     

     

     

    Posted by Sai Kilani (Mar 26, 2017 10:06 p.m.)
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What cause hardness of water

 

Posted by Satish Nehra (Mar 26, 2017 5:13 a.m.) (Question ID: 4513)

  • Answers:
  • Ans. Hard water contains dissolved magnesium and calcium ions. These make it more difficult for the water to form a lather with soap.

    • Temporary hardness is caused by dissolved calcium hydrogencarbonate (which is removed by boiling).
    • Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling).
    Answered by Naveen Sharma (Mar 26, 2017 6:54 a.m.)
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Why Cyst formation takes place in multiple fission ?

Posted by Tejas Shende (Mar 24, 2017 8:58 p.m.) (Question ID: 4484)

  • Answers:
  • During multiple fission large number of cells are produced number dvision of nuclues several times, these cells survive only in presence of protective covering , cyst.

    Answered by RAJENDRA SINGH (Mar 26, 2017 8:16 a.m.)
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To construct a ray diagram we use two rays which are so chosen that it is easy to know their direction after reflection from the mirror list two such rays and state the path of these rays after reflection in case of concave mirror

Posted by Shivani Sharma (Mar 23, 2017 5:02 p.m.) (Question ID: 4451)

  • Science exm is over den dis QN

     

    Posted by DiYa JoSepH.... (Mar 24, 2017 4:12 p.m.)
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Write molecular formula of first two members of homologous series of functional group cl

Posted by Shivani Sharma (Mar 23, 2017 4:56 p.m.) (Question ID: 4450)

  • Answers:
  • Two member of homologous series of functional group Cl are CH3Cl and C2H5Cl.

    Answered by RAJENDRA SINGH (Mar 23, 2017 6:28 p.m.)
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Name the term used for the trait that are exhibited externally. 

Posted by Ayush Meena (Mar 23, 2017 4:02 p.m.) (Question ID: 4447)

  • Answers:
  • Acquired traits

    Answered by Sunny Panwar (Mar 23, 2017 4:17 p.m.)
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For demonstrating the preparation of soap in the lab which of the following combination of an oil and a base would be most suitable : 

a.   Mustard oil & calcium hydroxide 

b.  Castor oil & calcium hydroxide 

c.  Turpentine oil & sodium hyroxide

d.  Mustard oil & sodium hydroxide

Posted by Aayush Rana (Mar 23, 2017 1:29 p.m.) (Question ID: 4442)

  • Answers:
  • Option D is correct 

    Answered by Ayush Meena (Mar 23, 2017 4:03 p.m.)
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Is Sponification reaction endothermic or exothermic. Plz answer fast

I need it too much

Posted by Aditya Sangwan (Mar 22, 2017 7:25 p.m.) (Question ID: 4401)

  • Answers:
  • Ans. Saponification is an endothermic reaction.

    Answered by Naveen Sharma (Mar 23, 2017 4:42 a.m.)
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When you add a few drops of acetic acid to a test-tube containing Sodium bicarbonate powder,which one of the following  is your observation?

A) No reaction takes place

B) A colourless Gas with pungent smell is released with brisk effervescence

C) A brown coloured Gas is released with brisk effervescence 

D) formation of bubbles of a colourless and odourless Gas.

Posted by Sudhanshu Baranwal (Mar 22, 2017 3:05 p.m.) (Question ID: 4391)

  • Answers:
  • Sure?

    Answered by Sudhanshu Baranwal (Mar 22, 2017 8:11 p.m.)
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  • D is the correct answer

     

    Answered by Parth Malhotra (Mar 22, 2017 4:51 p.m.)
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It is said," that will be considered the conservation of the forest ,we need to look at the stockholders," why?

 

 

Posted by Monika Chawla (Mar 22, 2017 6:04 a.m.) (Question ID: 4372)

  • Answers:
  • All the individual that have directly or indirectly assoicated with forest are called as stochholder like local people living in and around forest, goverment, industrialist that obtain raw material and common people. so, all these should look for conservation of forest.

    Answered by RAJENDRA SINGH (Mar 22, 2017 7:55 a.m.)
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It is said that ," when we consider that conservation of forest we need to look at the stockholders,"why?

Posted by Monika Chawla (Mar 22, 2017 6:02 a.m.) (Question ID: 4371)

  • Answers:
  • same as above.

    Answered by RAJENDRA SINGH (Mar 22, 2017 7:56 a.m.)
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What is ten percent law?

Posted by Shazia Maheen (Mar 21, 2017 10:21 p.m.) (Question ID: 4363)

  • Answers:
  • Ans. It was introduced by Raymond Lindeman. According to this law, during the transfer of energy from organic food from one trophic level to the next, only about ten percent of the energy from organic matter is stored as flesh. The remaining is lost during transfer, broken down in respiration, or lost to incomplete digestion by higher trophic level.

    Answered by Naveen Sharma (Mar 22, 2017 7:24 a.m.)
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Which size of plane mirror be required to see a man of 170 cm?

And describe how.

Posted by Sudhanshu Baranwal (Mar 21, 2017 9:18 p.m.) (Question ID: 4359)

  • Answers:
  • WhAt about spherical mirrors? 

    Answered by Sudhanshu Baranwal (Mar 22, 2017 3:09 p.m.)
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  • plalne mirror always form virtual and erect image of same size irrespective of the size of mirror.

    Answered by RAJENDRA SINGH (Mar 22, 2017 8:02 a.m.)
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What is archeopteryx

Posted by Ranveer Raj (Mar 21, 2017 9:13 p.m.) (Question ID: 4358)

  • Sir in this app there is a lots of mistake in ncert exemar problems question no. 4 and 6 mcq

     

    Posted by Ahquib Ahmad (Mar 21, 2017 9:18 p.m.)
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  • Answers:
  • Ans. Archaeopteryx is an iconic fossil, often thought of as the 'missing-link' between dinosaurs and birds. It was first described in 1861 by the German palaeontologist Hermann von Meyer.

    Answered by Naveen Sharma (Mar 21, 2017 10:35 p.m.)
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What is C2H5COOH?

Posted by Sudhanshu Baranwal (Mar 21, 2017 8 p.m.) (Question ID: 4354)

  • Answers:
  • Ans. It is Propanoic acid.

    Answered by Naveen Sharma (Mar 21, 2017 10:15 p.m.)
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Traits can be inherited but can not expressed. Justify the statement? 

Please answer fast because tomorrow will board exam

 

Posted by Sonika Garg (Mar 21, 2017 7:48 p.m.) (Question ID: 4350)

  • Answers:
  • All the traits that are inherited can not be expressed as recessive gene appear only when they are present in homozygous conditions as per first law of inheritance or law of dominance.

    Answered by RAJENDRA SINGH (Mar 22, 2017 8:05 a.m.)
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Why reuse is better than recycle 

Posted by Sumeet Mandal (Mar 21, 2017 7:28 p.m.) (Question ID: 4349)

  • Answers:
  • Because recycle conclude capital investment,energy investment and take too much time.

    But reuse doesn't conclude these all.

    Answered by Sudhanshu Baranwal (Mar 21, 2017 7:30 p.m.)
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What is niche? 

Plz Ans fast.

Tomorrow is exam.

Posted by Sudhanshu Baranwal (Mar 21, 2017 7:26 p.m.) (Question ID: 4348)

  • Answers:
  • Ans. A niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.

    Answered by Naveen Sharma (Mar 21, 2017 7:46 p.m.)
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how wavelength and refractive index and speed of light passing through prism are related

Posted by sukhman singh (Mar 21, 2017 4:25 p.m.) (Question ID: 4338)

  • Answers:
  • When rays of light passes through a glass prism, its wavelength decreases, refractive index increases and speed decreases.

    Answered by RAJENDRA SINGH (Mar 21, 2017 5:27 p.m.)
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What is difference between phenotype and genotype?

Posted by Shubham Manglekar (Mar 21, 2017 3:35 p.m.) (Question ID: 4334)

  • Answers:
  • Phenotype is the outer or visible appearance of organism. Like:tall, short.

    Genotype is the gene constitution of address of gene in the body of an organism.Like TT is gene pair for pure tall and tt is for pure short.

    Answered by Anupma Kumari (Mar 21, 2017 4:20 p.m.)
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Why Mendelèev's choice of compound as the basis for deciding the position of   an element in his table was a good one?How would this lead to element with similar chemecal properties being placed in the same group?

Posted by Mosaddique Ahmad Khan (Mar 21, 2017 3:19 p.m.) (Question ID: 4333)

how to calculate the formula of oxides and clorides

 

Posted by sana (Mar 21, 2017 2:43 p.m.) (Question ID: 4332)

  • Answers:
  • Formula of oxide can be obtained by crossing the valancy of elements and valancy of Oxygen (O) i.e.2.

    similarly, formula of chloride can be obtained crossing valancy of elements and Valancy of Chlorine (Cl) i.e. 1.

    Answered by RAJENDRA SINGH (Mar 21, 2017 5:30 p.m.)
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What is reproductive health

 

Posted by Tushar malik (Mar 21, 2017 2:21 p.m.) (Question ID: 4330)

  • Health health is the health related issues during the rerpoductev phases of individual that includes sexually transmitted disease, malnutrition during pregnancy and proper care of newely born child.

    Posted by RAJENDRA SINGH (Mar 21, 2017 5:33 p.m.)
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  • Answers:
  • The health influenced by reproduction.

     

    Answered by Sudhanshu Baranwal (Mar 21, 2017 2:29 p.m.)
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What is dams

 

Posted by Tushar malik (Mar 21, 2017 2:20 p.m.) (Question ID: 4329)

  • Answers:
  • Dams are artificially created water storing place created by obstructing the path of a river. its is created to controll flood, irrigation and production of hydroelectricity.

    Answered by RAJENDRA SINGH (Mar 21, 2017 5:35 p.m.)
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Will geographical isolation be a major factor in the speciation of organism that reproduces asexually? Why or why not?

Posted by Sudhanshu Baranwal (Mar 21, 2017 1:58 p.m.) (Question ID: 4328)

  • Answers:
  • Then why, ncert solutions of mycbseguide app says it is influence by geographical isolation.

    Answered by Sudhanshu Baranwal (Mar 21, 2017 6 p.m.)
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  • No because asexually reproducing organism do not depend on other individual as asexual mode needs only single parent.

    Answered by Anupma Kumari (Mar 21, 2017 4:22 p.m.)
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What is Snell's Law?

Posted by DiYa JoSepH.... (Mar 21, 2017 1:42 p.m.) (Question ID: 4327)

  • ThaNkk YoUU

    Posted by DiYa JoSepH.... (Mar 21, 2017 3:10 p.m.)
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  • Answers:
  • In refraction,   

    sin i/sin r=constant=refractive index of that media

    <hr/>

     

    Answered by Sudhanshu Baranwal (Mar 21, 2017 2:01 p.m.)
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  • The ratio of sine of angle of incidence to the sine of angle of refraction is a constant for the light of a given colour and given pair of medium..

    Sin i/sin r =  constant ..

    ..Refer page 174 of ncrt text.

    Answered by Rajendran Madhavan (Mar 21, 2017 2 p.m.)
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An element which is major constiuent of air

Posted by kart hi (Mar 21, 2017 1:08 p.m.) (Question ID: 4325)

  • Answers:
  • The major constituent of Air is Nitrogen element that constiture 78% of total volume of air.

    Answered by RAJENDRA SINGH (Mar 21, 2017 5:36 p.m.)
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  • O2  ie, oxygen ...

    Answered by Rajendran Madhavan (Mar 21, 2017 1:28 p.m.)
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What is optical density?

 

Posted by Anmol Kalra (Mar 21, 2017 12:39 p.m.) (Question ID: 4318)

  • Answers:
  • Optical density of a medium is the ability of that medium to refract light. Medium in which speed of light is more as compared to the other mediums is called optically rarer medium and the one in which speed of light is less is optically denser.

    The refractive index of optically denser medium is more as compared to R.I of optically rarer medium.

    Answered by Anupma Kumari (Mar 21, 2017 4:26 p.m.)
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  • Medium having greater value of refractive index is called optically denser medium, this means light will travel at slower speed in optically denser medium compared to in an optically rarer medium.

    The optical density of a medium is not the same as its physical density. The physical density of a material refers to the mass/volume ratio. The optical density of a material relates to the sluggish tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before reemitting it as a new electromagnetic disturbance. The more optically dense that a material is, the slower that a wave will move through the material.

     

    Answered by DiYa JoSepH.... (Mar 21, 2017 1:13 p.m.)
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