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

Who were conservatives?

Posted by Saif Sam (Jan 19, 2017) (Question ID: 1471)

A divergent lens has a focal length of 20cm.at what distance should an object of height 4cm from the optical centre of the lens be placed so that its image is formed 10cm away from the lens.find the size of the image also

Posted by BAIJU JOSEPH (Jan 18, 2017) (Question ID: 1449)

• Ans. Distance between the object and the lens (u )= -10cm
Focal length (f) = 20 cm
Distance between the image and the lens v = ?

Using Lens Formula

=>

=>

=>

=>

=> v = -20 cm

The image is formed on the same side as the object and since v is negative the image is erect and virtual and is formed at a distance 20 cm in front of the lens.

We know that

height of the object ho = 4 cm

=>

=>

=>

height of image = 8 cm

Answered by Naveen Sharma (Jan 18, 2017)
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Define homologous and analogues

Posted by sushanto choudhary (Jan 18, 2017) (Question ID: 1446)

• Homologous organs are those organs having same structure,origin and constituting parts but different functions are called homologous organs.

Analogous organs are the organs having the same functions but different in structure, origin and constituting parts.

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How do we come to know that which compound of carbon will make how much isomets and which rule do we follow while the making structure of an isomers?

Posted by Israr Khan (Jan 16, 2017) (Question ID: 1408)

• Isomerism is possible only with hydrocarbons having 4 or more carbon atoms, because only then we can have two or more different arrangements of carbon atoms.

No isomerism is possible in methane,ethane and propane because they contain only one,two or three carbon atoms respectively. Two isomers of the compound butane (C4H10) are possible and three isomers of compound pentane (C5H12) are possible. As the number of carbon atoms in an alkane molecule increases, the number of possible isomers increases rapidly.

Answered by Shweta Gulati (Jan 16, 2017)
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Evolution in organism is beneficial but how

Posted by Israr Khan (Jan 16, 2017) (Question ID: 1407)

• Evolution is good for life. Being able to adapt to the environment, as it is or if it changed, is how we ended here after all this millions or billions of years.

Evolution is also not something that happens in the life of an individual, but through generations, and usually in a gradual way, specially to reach something that an arbitrary line said that it is a different species.

And being the criteria for being sucessful, with evolution or without it (change always happen with enough time, be visible or not, but your species don't dissapear if is already very well adapted to the environment, just spawn different ones) is to live. What wasn't successful are species that weren't able to adapt or to evolve and end here in a way or another. Life is the evolution goal, not smarter, faster, stronger or nimbler, just survivor.

Answered by Payal Singh (Jan 17, 2017)
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• Your

Answered by Ajay Imandi (Jan 16, 2017)
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What is dihybrid in pea plant and also make me understand that how do the 16 pairs of peas formed?

Posted by Israr Khan (Jan 16, 2017) (Question ID: 1406)

Why sun appears to be red in evening and morning?

Posted by Israr Khan (Jan 16, 2017) (Question ID: 1404)

• At the time of sunrise and sunset when the sun is near the horizon,the sunlight has to travel the greatest distance through the atmosphere to reach us. During this long journey of sunlight, most of the shorter wavelength blue-color present in it is scattered out and away from our line of sight. So,the light reaching us directly from the rising sun consists mainly of longer wavelength red color due to which the sun appears red. Thus,at sunrise and sunset,the sun itself as well as the surrounding sky appear red.

Answered by Shweta Gulati (Jan 16, 2017)
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• During sunrise and sunset, the sun is at the farthest position. Here blue light gets scattered off and the red light, due to its larger wavelength, can travel a longer distance and hence reach our eyes. This we see the sun red.

Answered by Naveen Sharma (Jan 16, 2017)
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Why does sperm produce in lower temp.than our body?

Posted by Israr Khan (Jan 16, 2017) (Question ID: 1395)

• There is a thing called 'maturing'. Sperms are not produced at the time of ejaculation. Actually it will be produced for days. After that they will mature gradually. This maturing process needs a very careful handling. This needs many essential things like vitamins,hormones,proper temperature range,etc. Within the body, temperature controlling is not advisable, because some organs need heat for their proper functioning. Especially for a male many of his organs work good in elevated temperatures. So, the body is having a convenient place to grow the sperms thereby the outside, where it can keep the required temperature without affecting the major organs.

Heat is a factor that can cause great damage to DNA. In the testes where spermatogenesis (sperm meiosis) occurs you definitely do not want DNA damage occurring during or after this process as it could have devestating effects for the offspring. Hence, in a warm blooded human the testes are dropped from the body.

Answered by Naveen Sharma (Jan 16, 2017)
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Posted by PANKAJ BHAGAT (Jan 15, 2017) (Question ID: 1373)

• Biodegradable wastes decompose over time period but non -biodegradable not decompose over long time period

Posted by raman SINGH (Jan 15, 2017)
•

Biodegradable wastes are such waste materials which are and can be degraded by natural factors like microbes (e.g. bacteria, fungi and few more), abiotic elements like temperature, UV, oxygen, etc. Some examples of such wastes are food materials, kitchen wastes and other natural wastes

Non-biodegradable cannot be easily handled. Non-biodegradable wastes are those who cannot be decomposed or dissolved by natural agents. They remain on earth for thousands of years without any degradation. Hence the threat caused by them is also more critical. A notable example is the plastics which are a commonly used material in almost every field.

Answered by Naveen Sharma (Jan 15, 2017)
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Whether all ionic bonds are covalent bonds?

Posted by Akhil Gangadharan (Jan 14, 2017) (Question ID: 1364)

• No, ionic bonds are not covelent bonds. In ionic bonds transfer of electron takes place while in covelent bond sharing of electron takes place.

Answered by RAJENDRA SINGH (Jan 15, 2017)
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The angle of refraction in a glass of refractive index 1.5 is 19 degree . calculate the angle of incidence.

Posted by Rohit R Mahatungade (Jan 14, 2017) (Question ID: 1363)

• We know Refractive Index is

Given :

μ=1.5

r = 19

1.5 =

sin i =  1.5 * sin 1.9

=> sin i = 1.5 x 0.326

=> i = ${\mathrm{sin}}^{-1}$ ( 0.489)

=> i = $29.{23}^{\circ }$

Answered by Naveen Sharma (Jan 14, 2017)
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Used the term for the traitsthat are exhibited externaly

Posted by Jyoti Jasuja (Jan 14, 2017) (Question ID: 1356)

1. Traits that are exhibited externally are called acquired traits.
2. They are not passed on to the next generations.
3. For example, weight and handwriting

Answered by Naveen Sharma (Jan 14, 2017)
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Cause of lateral inversion

Posted by Jagruti Patel (Jan 14, 2017) (Question ID: 1353)

• The phenomenon of lateral inversion is neither limited to plane mirrors nor mirrors too. It is a manifestation of a basic property of matter called symmetry and an in depth discussion of which is beyond the scope of X level physics.

However, let us understand qualitatively. Take a coin’s head facing you and start rotating it; after you give a complete rotation to the coin you can see the head again. Now, rotate the coin 180 , what you see will be the tail. Now if the coin were transparent you would have seen a laterally inverted image of the head. Similarly, take a tracing paper and draw a B on it then see it through the other side of the paper. You’ll see a laterally inverted B. Thus, we conclude that after rotating a body it appears same if we rotate it by 360 and appears laterally inverted if we rotate it by 180 .

So viewing an object in a mirror is actually viewing at its 180 rotated state. This is the source of lateral inversion.

Answered by Naveen Sharma (Jan 14, 2017)
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Reaction when ethane reacts with chlorine

Posted by Arvind Thakur (Jan 13, 2017) (Question ID: 1349)

• Ethane reacts with chlorine by free radical halogenation in the presence of sunlight.

In the presence of sunlight, Cl2 breaks down (homolytically) to form two chlorine radicals. This is the initiation step. I will use the * symbol to indicate a radical, in fact this should be expressed using a superscript dot.

Cl2 => 2Cl*

The generated chlorine radical can then react with ethane to give an ethane radical (C2H5*) and HCl.
C2H6 + Cl* => C2H5* + HCl

The ethane radical then reacts with another molecule of chlorine to generate the initial halogenated product and another chlorine radical which can react again. This is the propagation step.
C2H5* + Cl2 => C2H5Cl + Cl*

The newly generated chlorine radical can now either react with another molecule of ethane (as above) or react with the halogenated product to give further halogenated products:
C2H5Cl + Cl* => C2H4Cl2

Answered by Vikrant Singh (Jan 14, 2017)
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What is cause of tindal effect?

Posted by ankur bansal (Jan 12, 2017) (Question ID: 1323)

• The scattering of light by particles in its path is called Tyndall effect. Light is scattered when it falls on various types of suspended particles in its path. An example of Tyndall effect is the way a beam of sunlight becomes visible as it passes through dust particles in the air of a room.

Answered by Shweta Gulati (Jan 17, 2017)
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•

Light scatterring by colloidal particles.
It is a sort of diffraction. The tyndall phenomenon is governed by the size of colloidal particles in the medium.

Answered by Naveen Sharma (Jan 13, 2017)
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• Brownian motion

Answered by Rakesh Sharma (Jan 12, 2017)
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Who arranged the modern periodic table

Posted by ashok kumar dora (Jan 12, 2017) (Question ID: 1322)

• HENRY MOSLE

Answered by Tanay Joshi (Jan 15, 2017)
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• henry mosley

Answered by Vikrant Singh (Jan 14, 2017)
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• The Modern Periodic Table was classified by Moseley. He altered the periodic table made by Mendelev and arranged the elements in increasing order of atomic numbers.

Answered by Naveen Sharma (Jan 13, 2017)
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• Mosley

Answered by ankur bansal (Jan 12, 2017)
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If a concave mirror has a focal length of 10cm, find the two positions where an object can be placed to give, in each case, an image twice the height of the object.

Posted by Shrey Raj (Jan 12, 2017) (Question ID: 1308)

• Given f = -10 cm

magnification is twice so taking

m = +2 and -2m = -v/u

2 = -v/u

v = -2u

1/f = 1/v + 1/u

-1/10 = -1+2/2u

u = -5

Now taking magnification as -2

m = -v/u

-2 = -v/u

v = 2u

1/f = 1/v + 1/u

-1/10 = (1+2)/2u

-2u = 30 or

u = -15

Answered by Naveen Sharma (Jan 12, 2017)
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• Ans.

The image twice the height of the object can

A) Virtual,erect and enlarged

Or

B) Real,inverted and enlarged

1) Virtual,erect and enlarge,

in this we will take m = 2

now, m = - v / u
=>2 = - v / u
=> 2u = -v

therefore, v = -2u

1/f=(1/v)+(1/u )
=> 1/(-10)=1/(-2u) + 1/u
=> 1/-10=(-1+ 2)/2u
=> 1/-10=1/2u
-10= 2u, u=-5 cm

B) Real,inverted and enlarge ,

in this we will take,  m = -2

now,m = - v / u
-2 = - v / u
- 2u = -v

therefore , v = 2u
1 / f  = (1 / v )+ (1 / u)
1 / (-10)  = 1 / (2u) + 1 / u
1 / - 10    = (1 + 2) / 2u
1 / - 10  =  3 / 2u
- 30 = 2u therefore , u  = - 15 cm

Therefore, an image twice the height of the object can be obtained when the object is placed at

A) 5cm from the concave mirror

B) 15cm from the concave mirror

Answered by Payal Singh (Jan 12, 2017)
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Difference between ethanol and ethanoic acid

Posted by Raman arora (Jan 10, 2017) (Question ID: 1268)

• Ethanol is the second member of alcohols. Its formula is C2H5OH. It is a colorless liquid having a pleasant smell and a burning taste. It does not contain hydrogen ions therefore, it is a neutral compound.

Ethanoic acid is the second member of carboxylic acids. Its formula is CH3COOH. It is a colorless liquid having a sour taste and a smell of vinegar. It is acidic n nature therefore, it turns red litmus blue.

To differentiate between ethanol and ethanoic acid chemically, perform the reaction of both the compounds with sodium hydrogencarbonate.

Ethanol gives no reaction with it while ethanoic acid gives brisk efferevesence on reation with it. When this gas is passed over lime water, it turns milky indicating the evolution of carbon dioxide gas.

Answered by Shweta Gulati (Jan 10, 2017)
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(a) the male reproductive system contains one portion that produces germ cells and other portion there delivers the germ cells.

(i) name the portions.

(ii) what is the male germ cell called?

(b) mention the structure of male germ cell and write its advantage

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1252)

• (A)

(i) The portion that produces germ is known as Testis and The portion that delivers the germ is Vas Deferens.

(ii) The male germ cell is called as Sperm.

(B) Male germ cell is called sperm. It has four parts:

1. Head: It contains a small acrosome and a large nucleus. Acrosome is responsible for penetrating the egg at the time of fertilization. 2. Neck: It is very short. The neck plays a role during the first cleavage of zygote.

3. Middle piece: The middle piece contains mitochondria which provide energy for the movement of sperm.

4. Tail: It is longer than head. It contains cytoplasm. The sperm swims by its tail in a fluid medium

Male germ cell is motile and small in size .its advantage is that it helps in fertilisation when it goes in female womb

Answered by Naveen Sharma (Jan 10, 2017)
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In an experiment Mendel obtained 1014 plants, out of which 787 are having round seeds and 227 had wrinkled seeds in F2 generation:

(a) what was the approximate ratio obtained in F2 generation?

(b) under which law do you find this ratio?

(c) why is this law so called?

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1250)

1. The approximate ratio obtained was 3: 1
2. Law of Seggregation or Law of purity of gametes.
3. The law states that the factors responsible for the two opposite characters remain in the F1 generation but seperate at the time of gamete formation.

Answered by Naveen Sharma (Jan 10, 2017)
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Explain the acidic character of oxides of elements down the group and across the period

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1247)

• In a group: The acidic characters decreases on moving down a group since the tendency to gain electrons decreases. Due to the increase in atomic size the force of attraction between the nucleus and the electron to be added becomes less.

In a period: The acidic character increases across a period from left to right since the tendency to gain across a period from left to right. As the atomic size reduces the effective nuclear charge acting on the valence electrons increases across a period from left to right

Answered by Naveen Sharma (Jan 10, 2017)
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An organic compound 'X' of molecular formula C2H4 on addition of h2 to give another compound 'Y' of molecular formula C2H6.'Y' on reaction with bromine in presence of Sunlight gives 'Z' of molecular formula C2H5Br.

(i)Name the compound 'X','Y'and'Z'

(ii) write the equation for the conversion of 'X' to 'Z' and name the type of reaction

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1246)

• Ans

Answered by Naveen Sharma (Jan 10, 2017)
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When we take 1 ml ethanol and 1 ml ethanoic acid along with a few drops of concentrated sulphuric acid in a test tube a  sweet smelling substance is formed. Name the compound and give the balanced chemical equation for the reaction. What do we call the reverse reaction  to give back alcohol and carboxylic acid which is used in the preparation of soap

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1245)

• Name of Compound formed is Ethyl Acetate.

Balance Reaction :

Reverse Reaction :  Saponification

Answered by Naveen Sharma (Jan 10, 2017)
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List any four practices by adopting which will help in the conservation of environment

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1244)

• (1) Dispose the waste after separating them into biodegradable and non-biodegradable waste material.

(2) Avoid unnecessary or wasteful packaging of products.

(3) Reuse carry bags.

(4) Plant trees. They will help to absorb excess carbon dioxide.

(5) Don’t burn any waste, especially plastics, for the smoke may contain polluting gases.

(6) Walk or cycle where it is safe to do so – walking is free; cycling can help to keep you fit.

(7) Use public transport wherever you can, or form a car pool for everyday travel.

Answered by Manish Gandhi (Jan 10, 2017)
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In what ways poor trivals are affected by dam development projects

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1243)

State the function of retina in the human eye. what type of cell are present in the retina?

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1242)

• The retina is a thin layer of tissue that lines the back of the eye on the inside. It is located near the optic nerve. The purpose of the retina is to receive light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition.

The retina processes light through a layer of photoreceptor cells. These are essentially light-sensitive cells, responsible for detecting qualities such as color and light-intensity. The retina processes the information gathered by the photoreceptor cells and sends this information to the brain via the optic nerve. Basically, the retina processes a picture from the focused light, and the brain is left to decide what the picture is.

Answered by Manish Gandhi (Jan 10, 2017)
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Identify from the following abiotic component of a pond ecosystem.  Water, algae, fish, aquatic plant and bacteria

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1241)

• Abiotic factors of a pond are all elements that are in or that affect the ecosystem of a pond other than the living, or biotic factors. So the answer is Water.

Answered by Manish Gandhi (Jan 10, 2017)
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Name two essential parts of complete flower

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1240)

• The two inner whorls in a complete flower consist of the stamens and the pistils. As to reproduction, they are considered the fertile and essential parts of a flower because they are directly involved in sexual reproduction, that is, in seed formation.

Answered by Naveen Sharma (Jan 10, 2017)
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• The essential parts of a flower can be considered in two parts

1) Vegetative part: consisting of petals and associated structures in the perianth

2) Reproductive or Sexual Parts

Answered by Manish Gandhi (Jan 10, 2017)
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Name the simplest ketone

Posted by Rohit Piproliya (Jan 10, 2017) (Question ID: 1239)

• Simplest Ketone is Propanone

Answered by Naveen Sharma (Jan 10, 2017)
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• Propanone (CH3COCH3) or Common name for this is Acetone.

Answered by Manish Gandhi (Jan 10, 2017)
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The image of an object in a concave mirror is twice the size of height of the object. The distance  between the object and image is 15cm. Find the focal length.

Posted by karthikeyan sureshbabu (Jan 07, 2017) (Question ID: 1170)