The mass and volume of $1/4$ mole of oxygen gas at $STP$ are respectively .....

How many protons are present in $1.8 \ g$ of $NH_{4}^{+}$?

How many atoms are contained in $5.6 \ L$ of oxygen gas at $STP$?

How many moles of $Al_2(SO_4)_3$ are present in $50 \ g$ of the substance?

$1 \ mL$ of water has $25$ drops. Let $N_0$ be the Avogadro number. What is the number of molecules present in $1$ drop of water? (Density of water $= 1 \ g / mL$)

Number of atoms in the following samples of substances is largest in