Question 1: What is gram atom? Why the concept of gram atom is useful in Chemistry?

Answer

Gram Atom:

Gram Atom of an element is defined as the atomic mass expressed in grams.

For example, atomic mass of C is 12 amu. If we take 12 g of Carbon, it will be 1 gram atom of C.

Importance of the concept of gram atom

We cannot see an atom and will never see it with naked eye.

Yes, we can count the number of atoms in a substance if we know how many gram-atoms of that substance do we have. Now, if we know the number of moles (or gram atoms) of reactants and products in a balanced chemical reaction, we can find how many atoms of the individual reactants combine together to give how many molecules of the individual products. Weighing it is yet another impossibility! On the other hand, we can see and weigh one gram-atom of an element (e-g, one mole of carbon is 12 g which can be seen and weighed).
Now, one gram atom contains a known number of atoms, called Avogadro’s number. Therefore, if we know the number of moles of an element participating in a chemical reaction, we can find the number of atoms of that element in the reaction. So the concept of gram atom gives us a better understanding of the role of an atom in a chemical reaction.