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1 mole of a substance = gram amt. / molecular mass(if it is compound) or atomic mass(if it is a element) of that substance
have a nice day............

one mole is the amount of substance that contain exactly as many no of particles as that are present in 12gram of carbon 12 atom

Suppose you want to carry out a reaction that requires combining one
atom of iron with one atom of sulfur. How much iron should you use?
How much sulfur? When you look around the lab, there is no device that
can count numbers of atoms. Besides, the merest speck (0.001 g) of iron
contains over a billion billion atoms. The same is true of sulfur.
Fortunately, you do have a way to relate mass and numbers of atoms.
One iron atom has a mass of 55.847 amu, and 55.847 g of iron contains
6.022 137 1023 atoms of iron. Likewise, 32.066 g of sulfur contains
6.022 137 1023 atoms of sulfur. Knowing this, you can measure out
55.847 g of iron and 32.066 g of sulfur and be pretty certain that you
have the same number of atoms of each.
The number 6.022 137 1023 is called Avogadro’s constant. For most
purposes it is rounded off to 6.022 1023. Because this is an awkward
number to write over and over again, chemists refer to it as a mole (abbreviated mol). 6.022 1023 objects is called a mole, just as you call 12
objects a dozen.
Look again at how these quantities are related.
55.847 g of iron 6.022 1023 iron atoms 1 mol of iron
32.066 g of sulfur 6.022 1023 sulfur atoms 1 mol of sulfur

a group of 6.022*10 to the power 23 ions/molecules/atoms is called a mole.
It so means that for eg. the atomic mass of oxygen is 16u. so no. of moles will be only 1 because 1 mole = atomic mass.

actually mole concept means the number of particles present in 1 mole of a substances is called as the mole concept.it is standardly take as 6.022*10to the power 23.it is also called as the avogadro constant..the value of 1 atom present on a mole is equal to this..

mole concept is the study of all those concepts which involve stoichiometric calculations.

* MOLE CONCEPT *
(Avogadro's Number)
Molecules and atoms are extremely small objects - both in size and mass. Consequently, working with them in the laboratory requires a large collection of them. How large does this collection need to be? A standard needs to be introduced. This standard is the "mole". The mole is based upon the carbon-12 isotope. We ask the following question: How many carbon-12 atoms are needed to have a mass of exactly 12 g. That number is NA - Avogadro's number. Thus, NA is defined by :
-> NA x (mass of carbon-12 atom) = 12 g
Careful measurements yield a value for NA = 6.0221367x10^+23. This is an incredibly large number - almost a trillion trillion. For example, if we stack NA pennies on top of one another how tall would the stack be? The answer is it would be so tall that the stack of pennies could reach the sun and back almost 500 million times!
A convenient name is given when there is an Avogadro's number of objects - it is called a "mole". Thus in the above example there was a mole of pennies.
1 mole = NA objects
The mole concept is no more complicated than the more familiar concept of a dozen : 1 dozen = 12 objects. From the penny example above one might suspect that the mass of a mole of objects is huge. Well, that is true if we're considering a mole of pennies, however a mole of atoms or molecules is a different story. Recall that the atomic mass unit (amu) is defined as 1/12 the mass of a carbon-12 atom. Consequently we have the relation
NA x 12 amu = 12 g
Thus, a mole of carbon-12 atoms has a mass of just 12 g. What about other atoms? In the periodic table the atomic mass of the elements is given. For example the atomic mass of magnesium is 24.305 amu. This is the average isotopic mass of naturally occurring magnesium. What is the molar mass of magnesium in grams? From the equation above we get 1 amu = 1g/NA or 1 amu = 1.66054x10^-24 g. Thus, a mole of magnesium atoms has a mass of NA x 24.305 amu x (1.66054x10^-24 g/amu) = 24.305 g. A mole of magnesium atoms has a mass of 24.305 g. This example demonstrates that the atomic mass of magnesium can be interpreted in one of two ways: (1) the average mass of a single magnesium atom is 24.305 amu or (2) the average mass of a mole of magnesium atoms is 24.305 g;
A similar conclusion follows for all of the other elements.

the mole is defined as the amount of a substance containing as many atoms, molecules,ions,electrons or other elementary entityies as there are carbon atoms in exactly 12 gram of C12.