Explain the terms: Avogadro constant,molar volume of $1$ mole of gas,and $STP$.

(N/A) Avogadro constant: The number of particles (atoms,molecules,or ions) present in $1$ mole of a substance is known as the Avogadro constant,which is $6.022 \times 10^{23} \ mol^{-1}$.
Molar volume: According to Avogadro's law,the volume of a gas $(V)$ is directly proportional to the number of moles $(n)$ at constant temperature and pressure. At $STP$,$1$ mole of an ideal gas occupies a volume of $22.71098 \ L \ mol^{-1}$.
$STP$ (Standard Temperature and Pressure): According to current $IUPAC$ recommendations,$STP$ is defined as a temperature of $273.15 \ K$ $(0^{\circ} C)$ and a pressure of $1 \ bar$ $(10^{5} \ Pa)$.