What is a group of `6.022 xx 10^(23)` particles known as ?

Mass of 6.022 xx10^(23) molecules of a gas is called ______

What name is given to the amount of substance containing 6.022 xx 10^(23) particles (atoms, molecules or ions) of a substance ?

What name is given to the number 6.022 xx 10^(23) ?

What volume shall be occupied by 6.022 xx 10^23 molecules of any gas at NTP?: