Mention the name given to the number of $6.022 \times 10^{23}$ particles.

Write the chemical formulae for the following compounds and find the ratio by mass of the combining elements in each one of them.
$(N=14 \ u, H=1 \ u, C=12 \ u, O=16 \ u, S=32 \ u)$
$(a)$ Methane
$(b)$ Carbon dioxide
$(c)$ Hydrogen sulphide

Calculate the number of moles of magnesium present in a magnesium ribbon weighing $12 \, g$. The molar atomic mass of magnesium is $24 \, g \, mol^{-1}$. (in $, mol$)

Which of the following contains the maximum number of molecules?

$(a)$ Write the chemical formula of sodium sulphate.
$(b)$ Name one element each that forms a diatomic and a tetraatomic molecule.

$(a)$ Write the chemical symbols of two elements:
$(i)$ which are formed from the first letter of the element's name.
$(ii)$ whose name has been taken from the names of the elements in Latin.
$(b)$ Define Avogadro's constant and molar mass. How are they related to one mole of an atom,molecule,or ion?