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Samarth Yadav 5 years, 8 months ago
Posted by Abhishek Rawat 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
After breathing air the most important thing needed most is water. Water is an essential commodity for the existence of life on Earth. Nowadays we know the miserable situation occurs when rainfall will be less .If rainwater decrease means the water content will be reduced. We need water to fulfill our unavoidable needs. We need water to drink, to cook food,for bath,for washing clothes ,for cleaning home .For all our needs we need water.Did you think about the situation in which their is no one drop of water in the world.?How frightening it will be .Hence we needed to conserve every one drop of water.
All living organisms need water to live. Without water, Earth will just be another rocky planet in the solar system.
Posted by Aarya Somkuwar 5 years, 8 months ago
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Aditya Gosaliya 5 years, 8 months ago
Aarya Somkuwar 5 years, 8 months ago
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Aateek Ali 5 years, 8 months ago
Aateek Ali 5 years, 8 months ago
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Aaquib Khan 5 years, 8 months ago
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Satyam Singh 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
The repetition of the sound, which is reflected from a high building or any such surface is called an echo. An echo can be heard only when the distance between the source of sound and the reflecting body is at least 17 m.
Posted by Abhishek Rawat 5 years, 8 months ago
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Mukhtar Ali 5 years, 8 months ago
Posted by Abhishek Rawat 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
Dalton’s atomic theory can be explained as follows:
1) Matter is made up of atoms. Atoms are indivisible and indestructible.
2) All atoms of a certain element are identical in mass and properties.
3)Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms.
In short we can say that,
Dalton’s atomic theory states that matter consists of indivisible particles called atoms of a given element are all identical and can neither be created nor destroyed. Compounds are formed by combination of atoms in simple ratios to give compound atoms (molecules).
Posted by Divya Thakur 5 years, 8 months ago
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Satyam Singh 5 years, 8 months ago
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Meghna Thapar 5 years, 7 months ago
Inertia is the property of a body by virtue of which it opposes any agency that attempts to put it in motion or, if it is moving, to change the magnitude or direction of its velocity.
Posted by Rohit Thakur 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
We have to initially find the Kinetic difference,
The formula for Kinetic difference is,
K.E{tex}=\frac{1}{2} \times m \times u^{2}{/tex}
{tex}=\frac{1}{2} \times 5 \times 10^{2}{/tex}
{tex}=\frac{1}{2} \times 5 \times 100{/tex}
{tex}=5 \times 50{/tex}
K.E = 250 \ J
The, Potential energy of the body is 250 J, when it reaches the highest point.
Loss in K.E = gain in P.E
→ P.E = 250 J
And the formula for potential difference is,
{tex}PE =m \times g \times h{/tex}
{tex}250=5 \times 10 \times h{/tex}
{tex}250=50 \times h{/tex}
{tex}h=\frac{250}{50}{/tex}
{tex}h = 5 \ m{/tex}
Posted by Md Nasim 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
Retardation means negative acceleration. The velocity of a body may increase or decrease .Acceleration takes place when the velocity of a body changes. So when the velocity of a body increase, the acceleration is said to be positive and when the velocity of a body decrease, the acceleration is said to be negative(Retardation).A body is said to be retarded if its velocity is decreasing. Eg: a train is said to be retarded when it slows down on reaching a station,i.e. the velocity decreases.Retardation is acceleration with negative sign. Or negative value of acceleration shows that the velocity of a body is decreasing.
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Jatin Vats 5 years, 8 months ago
Yogita Ingle 5 years, 8 months ago
The cooling in a desert cooler is caused by the evaporation of water. A desert cooler cools better on a hot and dry day because the higher temperature on a hot day increases the rate of evaporation of water and the dryness of air (low humidity of air) also increases the rate of evaporation of water. And due to increased rate of evaporation of water, a desert cooler cools better on a hot and dry day.
Raj Shekhar 5 years, 8 months ago
Posted by Soniya Hembram 5 years, 8 months ago
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Harneet Kaur 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
The chemical formula of baking powder is NaHCO3.
Molecular mass of baking powder (NaHCO3) = 23 + 1 + 12 + 3 X 16
= 84g/mole
Posted by Churnitha Bethini 5 years, 8 months ago
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Meghna Thapar 5 years, 7 months ago
Projectile is a body thrown with an initial velocity in the vertical plane and then it moves in two dimensions under the action of gravity alone without being propelled by any engine or fuel. Its motion is called projectile motion. The path of a projectile is called its trajectory.
Examples:
A packet released from an airplane in flight.
A golf ball in flight.
A bullet fired from a rifle.
A jet of water from a hole near the bottom of a water tank.
Projectile motion is a case of two-dimensional motion .Any case of two dimensional motion can be resolved into two cases of one dimensional motion -one along the x-axis and the other along the y-axis.
Posted by Vishal Nath 5 years, 8 months ago
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Rajneesh Payal 5 years, 8 months ago
Yogita Ingle 5 years, 8 months ago
The mole is the amount of substance that contains the same number of particles (atoms/ ions/ molecules/ formula units etc.) as there are atoms in exactly 12 g of carbon-12.
Mass of 1 mole of a substance is called its molar mass.
Posted by Jain Rounak 5 years, 8 months ago
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Meghna Thapar 5 years, 7 months ago
Mole Concept:
We know that a dozen is a collect ion of 12 substances, a century is a collection of 100 substances and a gross is a collection of 144 substances. We use the terms dozen, century, gross etc. to express a certain quantity of a substance. Similarly, a mole is a word used to describe a collection of particles i.e. atoms, molecules or ions.
1 mole of a substance is equal to its atomic mass or molecular mass expressed in grams. The atomic mass expressed in grams is the gram atomic mass. The molecular mass expressed in grams is the gram molecular mass.
For example, The atomic mass of sodium is 23 grams.
Therefore, 23 grams of sodium is equal to one mole of sodium atoms.
Similarly, the molecular mass of oxygen (O2) = 2 × Atomic mass of oxygen
= 2 × 16
= 32 g
Avogadro experimentally found that one mole of any substance always contained 6.022 × 1023 particles.
This number is called the Avogadro’s number, denoted by N0.
Posted by Sourabh Kashyap 5 years, 5 months ago
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Posted by B Dhanush 5 years, 8 months ago
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Yogita Ingle 5 years, 8 months ago
Thomson's model of an atom:
1. An atom consists of a sphere of positive charge with negatively charged electrons embedded in it.
2. The positive and the negative charges in an atom are equal in magnitude due to which an atom is electrically neutral.
Rutherford's model of an atom:
1. There is a positively charged, highly densed centre in an atom called the nucleus. Nearly the whole mass of an atom resides in the nucleus.
2.The electrons revolve around the nucleus in circular path.
3. The size of the nucleus is very small compared to the size of an atom.
Bohr's model of an atom:
1.An atom is made up of 3 particles electrons, protons and neutrons. Due to the presence of equal number of electrons and protons, atom on the whole is electrically neutral.
2. The protons and neutrons are located inside the nucleus due to which nucleus is positively charged.
3. The electrons revolve around the nucleus in fixed paths called orbots or shells or energy levels. The energy levels are represented as K,L,M,N or 1,2,3,4,5,.....
4. There is a limit to the number of electrons each energy level can hold. It is given by the formula 2n^2 where n is the orbit number .
5. Each energy level is associated with fixed amount of energy, the shell nearest to the nucleus having minimum amount of energy and the one farthest having maximum energy.
6. There is no change in the energy of electrons as they keeping revolving in the same shell and the atom remains stable.
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Yogita Ingle 5 years, 8 months ago
Bacteria are unicellular prokaryotic organisms capable of surviving in unusual habitats. Their cellular body is protected by a cell membrane as well as cell wall. The cell wall of bacteria is composed of peptidoglycan that is capable of withstanding different conditions. Some bacteria also form spores that can withstand unfavourable conditions. These spores germinate and give rise to new bacterial cells on return of favourable conditions.
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