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What is disease and define it's types 

Posted by Simranvir Sondhi (Jan 19, 2017) (Question ID: 1462)

  • Answers:
  • In Simple words disease is as name word itself suggests without ease.

    Disease is an abnormal condition of a part, organ, or system of an organism resulting from various causes, such as infection, inflammation, environmental factors, or genetic defect, and characterized by an identifiable group of signs, symptoms, or both.

    <font face="Arial">Types of Diseases</font>

    <font face="Arial">•</font>  <font face="Arial">Acute diseases</font>

    <font face="Arial">-</font>  <font face="Arial">The symptoms appear suddenly.</font>

    <font face="Arial">-</font>  <font face="Arial">These diseases are short term ie the symptoms last for short period of time.</font>

    <font face="Arial">-</font>  <font face="Arial">Eg. Influenza (Flu) , Common cold.</font>

    <font face="Arial">• Chronic diseases</font>

    <font face="Arial">-</font>  <font face="Arial">These diseases long term diseases.</font>

    <font face="Arial">-</font>  <font face="Arial">Their symptoms develop gradually and are long lasting.</font>

    <font face="Arial">-</font>  <font face="Arial">Eg. TB, Cancer etc</font>

    <font face="Arial">• Congenital diseases</font>

    <font face="Arial">-</font>  <font face="Arial">These are inborn diseases i.e. present from birth.</font>

    <font face="Arial">-</font>  <font face="Arial">Most of the diseases are permanent and generally not easily curable.</font>

    <font face="Arial">-</font>  <font face="Arial">They could be due to genetic abnormality or metabolic disorder.</font>

    <font face="Arial">-</font>  <font face="Arial">Eg. Down syndrome, Hemophilia, colour blindness, Sickle cell anaemia etc</font>

    <font face="Arial">• Acquired diseases</font>

    <font face="Arial">-</font>  <font face="Arial">The diseases which a person gets in his or her life time (i.e. after birth) are called acquired diseases.</font>

    <font face="Arial">-</font>  <font face="Arial">Acquired diseases are classified in to two categories</font>

    <font face="Arial">1)</font>  <font face="Arial">Communicable diseases (Infectious diseases)</font>

    <font face="Arial">2)</font>  <font face="Arial">Non-communicable diseases (Non-infectious diseases)</font>

    <font face="Arial">1) Communicable Diseases</font>

    <font face="Arial">•</font>  <font face="Arial">Communicable diseases are caused by pathogens such as virus, bacteria, protozoan, worms or fungi.</font>

    <font face="Arial">•</font>  <font face="Arial">The organism causing the disease may be transmitted from an infected person to another by means of air, water, food, physical contact or insects (vectors).</font>

    <font face="Arial">•</font>  <font face="Arial">Communicable diseases can be further classified on the basis of the causative agents like Bacterial diseases, Viral diseases, Helminth diseases, Fungal diseases etc.</font>

    <font face="Arial">2) Non-Communicable Diseases</font>

    <font face="Arial">•</font>  <font face="Arial">These are non infectious diseases ie do not spread from an infected person to other healthy person</font>

    <font face="Arial">•</font>  <font face="Arial">These diseases include deficiency diseases, degenerative diseases, cancer etc.</font>

    Answered by Naveen Sharma (Jan 19, 2017)
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Bhor's atomic model

Posted by NITIN KUMAR (Jan 17, 2017) (Question ID: 1435)

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  •  

    In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. The motion of the electrons in the Rutherford model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation; thus, the electrons would lose energy and spiral into the nucleus. To remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump.

     

    Answered by Naveen Sharma (Jan 17, 2017)
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How can we define sound?

Posted by Ashish Sharma (Jan 17, 2017) (Question ID: 1427)

  • Answers:
  • Sound is a vibration that propagates as a typically audible mechanical wave of pressure and displacement, through a transmission medium such as air or water.

    Answered by Payal Singh (Jan 17, 2017)
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  • Vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.

    Answered by Naveen Sharma (Jan 17, 2017)
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What is molar mass

 

Posted by Abhisek Yadav (Jan 16, 2017) (Question ID: 1409)

  • Molar mass is the amount of mass in one mole of a substance. A mole is used in chemistry as a counting unit indicating the amount of ions, atoms, molecules or formula units in a specific chemical sampl

    Posted by Payal Singh (Jan 17, 2017)
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  • Answers:
  • The mass of one mole of the substance is called molar mass of that substance. Its units are g/mol. If the substance is atomic, its molar mass is equal to gram atomic mass. If the substance is molecular, its molar mass is equal to gram molecular mass.

    Molar mass of magnesium (Mg)= 24g/mol

    Molar mass of oxygen (O2)= 2x16= 32g/mol

    Answered by Shweta Gulati (Jan 16, 2017)
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A stone of mass 4gm is to be thrown into a well. The sound is to be heard after 4sec .find the depth of well if (g=10m/s2)and speed of sound is 340m/s.

Posted by Kd Solanky (Jan 14, 2017) (Question ID: 1369)

  • Answers:
  • For the 1st part the stone is falling under gravity. Let t1 be the time from release to splashdown.

    d =depth

    So d= gt12/2  -  (1)

    After splashdown the sound travels back up. Using 330m/s for the speed of sound this gives:

    d=330×t2  (2)

    We also know that:

    t1+t2=4s  (3)

    Combining (1)and(2) we get:

    330t2= gt12/2

    From (3)⇒

    t2=(4−t1)

    So:

    330(4−t1)=gt12/2

    5t12+330t-1320=0

    t12+66t-264=0

    Solving this quadratic equation using Discriminant formula and ignoring the -ve root we get

    t1=3.78s

    So t2=4−3.78=0.22s

    So d=330×t2=330×0.22=72.6m

    Answered by Shweta Gulati (Jan 17, 2017)
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  • this is 19h85 instead of 19h5

    Answered by Naveen Sharma (Jan 16, 2017)
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  • Ans. Let Depth of Well = h 

    tstone + tsound = 4            .................. (1)

    For  tstone (free-falling body ) :

    h = 12gt2=> t = 2hg

    tstone= 2h10

    = > tstone = h5

    For tsound (uniform motion): 

    h = ut=> t = hu

    tsound = h340

    Put Both values  values in eq (1), We get 

    h5 + h340 = 4

    => h5 = 4 - h340

    Squaring both sides

    h5 = 16 + h23402 - 2h85

    => h2115600 + 16 = h5 + 2h85

    => h2115600  - 19h5  + 16 = 0 

    Solve for h and you ll have answer

    Answered by Naveen Sharma (Jan 16, 2017)
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Find the energy in kilowatt hours consumed by a machine of power 500watts? 

 

Posted by Archi tiwari (Jan 12, 2017) (Question ID: 1327)

  • Answers:
  • We know 1 Kw = 1000W

    Power of machine in Kw:  500/1000  = 1/2 Kw

    Power consumption in 1 hour = 1/2 * 1 = 1/2Kwh

     

    Answered by Naveen Sharma (Jan 13, 2017)
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0.18 grams of glucose contains how many atoms

Posted by SUNITHA D (Jan 12, 2017) (Question ID: 1325)

  • Answers:
  • So, glucose's molecular formula is C6H12O6, which means that every molecule of glucose contains Six carbon atoms ,Twelve hydrogen atoms, Six oxygen atoms.

    Molar mass of C = 12 g mol-1

    Molar mass of H = 1 g mol-1 

    Molar mass of O = 12 g mol-1 

    There fore,

    Molar mass of C6H12O6=(6x12) + (12x1) + (6x16) = 72 + 12 + 96 = 180 g mol-1

    Now we can calculate the number of moles of glucose as follows: 

    The number of moles of glucoses n  = w/M , where w is weight in gram and M is molar mass.

    => 0.18/180 = 10-3 moles

    It is also possible to get the number of atoms in the given sample by multiplying the number of moles with Avogadro number, NA 

    Thus

    the number of atoms = n.NA, Where NA = 6.022 x 1023

    In above glucose sample, 

    the no. of glucose atomes  = 10-3 x 6.022 x 1023 = 6.022 x 1020 

     

     

    Answered by Naveen Sharma (Jan 13, 2017)
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0.025 moles of methane contain how much grams

Posted by SUNITHA D (Jan 12, 2017) (Question ID: 1324)

  • Answers:
  • Gram atomic mass of methane=CH4=12+4×1

    =16  no of moles=given mass÷gram atomic mass

    0:025=given mass÷16

    So,given mass=16×0:025

    Given mass=0:4 gram

    Answered by Ghanshyam Kumar (Jan 13, 2017)
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If 16 g of oxygen contains 1 mole of oxygen atoms, calculate the mass of one atom of oxygen. 

Posted by pratham srivastav (Jan 12, 2017) (Question ID: 1312)

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  • Ans.

    Molar mass of a substance is a mass of 6.023 X1023 molecules.

    Molar mass of Oxygen molecule i.e N is 2 X 8 = 16 g.

    Thus 6.023 X 1023 molecules weigh = 16 g

    1 molecule of Oxygen weighs = 16/6.02 X 1023 = 2.66 X 10-23 g

    Answered by Naveen Sharma (Jan 12, 2017)
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  • Ans. The mass of 1 atom = Gram atomic mass of atom/ 6.022 × 1023

    So, the mass of 1 atom of oxygen = Gram atomic mass of oxygen atom/ 6.022 × 1023 = 16g/ 6.022 × 1023 =

    2.66 × 10-23 g

    Answered by Payal Singh (Jan 12, 2017)
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If one mole of nitrogen molecules weighs 28 g, calculate the mass of one molecule of nitrogen in grams. 

Posted by pratham srivastav (Jan 12, 2017) (Question ID: 1311)

  • Answers:
  • Answer: The mass of 1 atom = Gram atomic mass of atom/ 6.022 × 1023

    So, the mass of 1 atom of nitrogen = Gram atomic mass of nitrogen atom/ 6.022 × 1023 = 28g/ 6.022 × 1023 =

    4.65 × 10-23 g

    Answered by Payal Singh (Jan 12, 2017)
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  • Ans. Molar mass of a substance is a mass of 6.023 X1023 molecules.

    Molar mass of nitrogen molecule i.e N is 2 X14 = 28 g.

    Thus 6.023 X 1023 molecules weigh = 28 g

    1 molecule of nitrogen weighs = 28/6.02 X 1023 = 4.65 X 10-23 g

    Answered by Naveen Sharma (Jan 12, 2017)
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In an experiment, 4.9g of copper oxide news obtained nfrom 3.92g  of copper . In another experiment,4.55g of copper oxide gave, on reduction, 3.64 g of copper . Show that these figure verify the law of constant proportion

Posted by Tanveer Singh (Jan 12, 2017) (Question ID: 1310)

  • Answers:
  • Case I

    Mass of copper= 3.92g

    Mass of copper oxide= 4.9g

    % of copper in oxide = (Mass of copper/Mass of copper oxide) x 100

    = 80%

    So, % of oxygen = 100-80= 20%

     

    Case II

    Mass of copper= 3.64g

    Mass of copper oxide= 4.55g

    % of copper in oxide = (Mass of copper/Mass of copper oxide) x 100

    = 80%

    % of oxygen= 100-80=20%

    Thus,copper oxide prepared by any of the given methods contains copper and oxygen in the same proportion by mass.Hence, it proves the law of constant proportions.

    Answered by Shweta Gulati (Jan 17, 2017)
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How to derive  speed = wavelength * frequency

 

 

 

 

 

Posted by Tanveer Singh (Jan 12, 2017) (Question ID: 1307)

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  • As we know, speed= Distance travelled/Time taken

    Suppose a wave travels a distance λ which is its wavelength in time T,

    λ / T

    Here T is the time taken by one wave. 1/T becomes the number of waves per second and is known as frequency of the wave.

    Thus v = λ x f

    i.e. Speed = Wavelength x Frequency

    Answered by Shweta Gulati (Jan 17, 2017)
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what is canal ray? 

Posted by Suresh Goyal (Jan 12, 2017) (Question ID: 1303)

  • Answers:
  • Canal rays: These are also known as anode rays which are made up of positively charged material particles known as protons. They are called as canal/anode rays because they seems to be coming from a perforated anode used in a discharge tube experiment. The charge to the mass ratio (e/m ratio ) is not constant for these rays, and has been found different for different gases used in the discharge tube. The mass of proton has been found to be nearly equal to that of hydrogen atom.(nearly 1).

    Answered by Naveen Sharma (Jan 12, 2017)
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  • An anode ray (also positive ray or canal ray) is a beam of positive ions that is created by certain types of gas discharge tubes. They were first observed in Crookes tubes during experiments by the German scientist Eugen Goldstein, in 1886.

    Answered by Payal Singh (Jan 12, 2017)
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  • positively rays

    Answered by Suresh Goyal (Jan 12, 2017)
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Can water boil at 0 degree celcius? 

Posted by Kanha Dhameja (Jan 11, 2017) (Question ID: 1291)

  • Answers:
  • Yes you can! Only if By any means you make the vapour pressure of water at the 'desired' temperature (0°C if you like) equal to (or greater) the atmospheric pressure of that place, your water will boil. 
    Aliter, reduce atmospheric pressure. Keep the water in vacuum.

    Answered by Naveen Sharma (Jan 12, 2017)
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Explain the uses of sonar

Posted by SUNITHA D (Jan 10, 2017) (Question ID: 1266)

  • Answers:
  • SONAR is an apparatus which is used to find the depth of a sea or to locate the under-water things like shoals of fish,shipwrecks, and enemy submarines. It works by sending short bursts of ultrasonic sound from a ship down into sea-water and then picking up the echo produced by the reflection of ultrasonic sound from under-water objects. Thus, the time it takes for an echo to return is used to find out how far away something is. 

    Answered by Shweta Gulati (Jan 10, 2017)
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    • Sound navigation and ranging
    • It is used in detected sumarine , rocks , etc
    • It receives the depth of the sea
    Answered by Raman arora (Jan 10, 2017)
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What is STM? How iy works?

Posted by Bhavy Bansal (Jan 07, 2017) (Question ID: 1139)

  • Answers:
  • A scanning tunneling microscope (STM) is a non-optical microscope that works by scanning an electrical probe tip over the surface of a sample at a constant spacing. This allows for a 3D picture of the surface to be created.

    <h2><a name="_How_STM_Works"></a>How STM Works</h2>

    The STM sample must conduct electricity for the process to work. The STM uses a tip that ends in a single atom and a voltage is passed though the tip and the sample. Electrons use a quantum mechanical effect to ‘tunnel’ from the tip to the sample or vice versa. The current that results depends upon the distance between probe tip and sample surface. The tip is attached to a piezoelectric tube and voltage applied to the piezo rod is altered to maintain a constant distance for the tip from the surface. Changes in this voltage allows a three dimensional picture of the material surface to be built up as the tip is scanned back and forth across the sample.

    Figure 1. STM tip

    <h2><a name="_Resolution"></a>Resolution</h2>

    An STM can have a resolution down to 0.2nm, small enough to resolve individual atoms.

    <h2><a name="_Applications"></a>Applications</h2>

    Due to the remarkable detail and STM can give about the surface of a material, they are very useful for studying friction, surface roughness, defects and surface reactions in materials like catalysts. STMs are also very important tools in research surrounding semiconductors and microelectronics.

    Answered by Vikrant Singh (Jan 07, 2017)
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What is workdone in lifting a body of mass 5 kg vertically through 9 m?

 

Posted by Neeraj Yadav (Jan 07, 2017) (Question ID: 1135)

  • Workdone=F×s×cos thita

    =F×s×cos 90

    =F×s×0

    =0 then the workdone by lift is 0

    Posted by Ghanshyam Kumar (Jan 07, 2017)
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what is speed of sound?

 

Posted by Ankit Kumar (Jan 07, 2017) (Question ID: 1124)

  • Answers:
  • Speed of sound is 340.29 m/s.

    Answered by shruti dadhwal (Jan 07, 2017)
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  • speed of sound at sea level =

    340.29 m / s

    Answered by Vikrant Singh (Jan 07, 2017)
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The density of gold is 19g/cm³.find the volume of 95 g of gold.

 

Posted by Neeraj Yadav (Jan 05, 2017) (Question ID: 1099)

  • Answers:
  • Density = 19g/cm3

    Mass = 95 g

    Volume = ?

    Volume = Mass/Density

    Volume = 95/19

     Volume = 5 cm3

    Answered by Shivi Singhal (Jan 06, 2017)
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  • Density - mass/volume

    19 = 95/V.

    V= 95/19

    V= 5 cm3

    Answered by RAJENDRA SINGH (Jan 05, 2017)
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Symposium on diversity of living organisms

Posted by Kunal Sharma (Jan 05, 2017) (Question ID: 1095)

  • Answers:
  • Diversity of living organisms is the presence of differnet kinds of oragnisms varying in shape, size, colour and other observable properties to adjust in different climatic conditions.

    Answered by RAJENDRA SINGH (Jan 05, 2017)
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Is frequency of sound decreases as it travels a long distance?

Posted by Priyanshu Dixit (Jan 05, 2017) (Question ID: 1085)

  • Answers:
  • Frequncy of sound wave decreases  as it travels a long distance due to decrease in energy level.

    Answered by RAJENDRA SINGH (Jan 05, 2017)
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What is the mass of 5m³ of cement of density 3000kg/m³

 

Posted by Neeraj Yadav (Jan 04, 2017) (Question ID: 1076)

  • Answers:
  • As we know,                                                                     density = mass/volume

    So,density=3000kg/m3.                                              volume= 5m3

        Mass= ?

    Therefor,    3000 =mass/5

                   Mass =15000 kg

    -------------------------------------------------------------------

    Answered by Sudhanshu Yadav (Jan 05, 2017)
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Define isotopes

Posted by MAN MEET (Jan 04, 2017) (Question ID: 1074)

  • Answers:
  • Isotopes are the atoms of same element having same atomic number but different mass number and different atomic masses. 

    For example,  chlorine having same atomic number but different mass number. 

    Answered by Sudhanshu Yadav (Jan 05, 2017)
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Calculate the pressure exerted by a block of 45N if the surface area in contact is 2.5m2

Posted by daksh dang (Jan 03, 2017) (Question ID: 1048)

  • Answers:
  • Pressure = force/area

    = 45/2.5 = 18

    Answered by Ahmed Hamzah (Jan 08, 2017)
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  • Pressure = Force/Area

                  = 45/2.5

    Answered by Jayan Agarwal (Jan 03, 2017)
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compare the power at which each of the follwing is moving upwards against the fore of gravity 1g 210m/s 

1) a butterfly of mass 1g that flies upward at a rate of 0.5m/s 

2) a 250g squirrel climbing on a tree at a rate of 0.5 m.s

Posted by savitajain jain (Jan 02, 2017) (Question ID: 993)

Name the phylum in which the animals have water vascular system

Posted by seema Shukla (Dec 31, 2016) (Question ID: 972)

  • Answers:
  • The phylum of animals that have a peculiar(strange) water-driven tube system is Echinodermata that they use for moving around, food and waste transportation and respiration.

    Examples are Starfish and Sea Cucumber

    Answered by Krish Gulati (Dec 31, 2016)
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Explain nitrogen cycle

Posted by Nivedita Jha (Dec 31, 2016) (Question ID: 969)

  • It also involves Amonification..

    Posted by Nivedita Jha (Jan 01, 2017)
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  • Answers:
  • The nitrogen cycle involves three major steps: Nitrogen Fixation, Nitrification, and Denitrification. It is a cycle within the biosphere which involves the atmosphere, hydrosphere, and lithosphere. Nitrogen is found in several locations, or reservoirs. It is most prevalent in sediments and rocks, second in the atmosphere (78%).

    Neither plants or animals can obtain nitrogen directly from the atmosphere. Instead, they depend on a process known as Nitrogen Fixation. Key players in this process are legumes and the Symbiotic Bacteria which are associated with the legume's root nodules. These bacteria are known as nitrogen-fixing bacteria. These organisms convert nitrogen in the soil to ammonia, which can then be taken up by plants. This process also occurs in aquatic ecosystems, where cyanobacteria participate.

    After nitrogen has been fixed, other bacteria convert it into nitrate, in a process known as nitrification. In the first step of this process, Nitrosomonas convert ammonia into nitrite, and in the second step, nitrite is converted into nitrate, by Nitrobacter. This nitrate is then consumed by plants.

    The final aspect of the nitrogen cycle is the process of denitrification. This process is performed by a variety of microscopic bacteria, fungi, and other organsims. Nitrates in the soil are broken down by these organsisms, and nitrogen is released into the atmosphere. This complete the cycle.

    Answered by Naveen Sharma (Dec 31, 2016)
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what is hemaphrodite?

Posted by vishakha bora (Dec 31, 2016) (Question ID: 968)

  • Answers:
  • Hermaphrodite is a person or animal having both male and female sex organs or other sexual characteristics, either abnormally or (in the case of some organisms) as the natural condition.

    Answered by Devanshu Agarwal (Dec 31, 2016)
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A piece of iron of density 7.8 g/cmand volume 100 cm3  is fully immersed in water (density of water is 1 g/cm3). Calculate 

1. Weight of iron piece in air

2. Upthrust of water on iron piece

3. Apparent weight of iron piece in water (g = 10 m/s2)

Posted by Ahmed Hamzah (Dec 30, 2016) (Question ID: 964)

  • Answers:
  • In the first one, why do we divide it by 1000?

    Answered by Ahmed Hamzah (Jan 01, 2017)
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  • Thank you so much

    Answered by Ahmed Hamzah (Jan 01, 2017)
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  • Ans.

    Answered by Naveen Sharma (Dec 31, 2016)
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derive an expression for the potential energy ofthe body. calculate P.E of the body of mass 10kg at a height of 10m

 

Posted by preethi chennagouni (Dec 30, 2016) (Question ID: 956)

  • Answers:
  • The Potential energy of a body is calculated using the formula

    P. E. = mgh

    where m= mass of the body 

    g= acceleration due to gravity ( you can take it as 10 ms-2 for simple calculations otherwise 9.8 ms-2)

    h= height of the body

     

    In this question we are given

    Mass of body, m=10kg

    Height of body, h=10 m

    Using the formula, 

    P. E. =10*9.8*10=980J

    Answered by Shweta Gulati (Dec 30, 2016)
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