Name the international organisation which approves the names given to the elements. Write the symbol of tungsten.

The difference in the mass of $100 \, mol$ each of sodium atoms and sodium ions is $5.48002 \, g$. Compute the mass of an electron.

$(i)$ $(a)$ What do you understand by $1 \text{ amu}$ or $1 \text{ u}$?
$(b)$ How is it linked with relative atomic mass?
$(ii)$ How do we know the presence of atoms if they do not exist independently for most of the elements?

Calculate the number of particles in each of the following:
$(a)$ $48 \,g$ of $Mg$
$(b)$ $8 \,g$ of $O_2$
$(c)$ $0.1$ mole of carbon (Atomic mass $Mg = 24 \,u, O = 16 \,u, C = 12 \,u$,Avogadro constant $= 6.022 \times 10^{23}$)

What is the $SI$ prefix for each of the following multiples and submultiples of a unit?
$(a)$ $10^{3}$
$(b)$ $10^{-1}$
$(c)$ $10^{-2}$
$(d)$ $10^{-6}$
$(e)$ $10^{-9}$
$(f)$ $10^{-12}$

Which of the following symbols of elements are incorrect? Give their correct symbols:
$(a)$ Cobalt $CO$
$(b)$ Carbon $c$
$(c)$ Aluminium $AL$
$(d)$ Helium $He$
$(e)$ Sodium $So$