What amount of dioxygen (in gram) contains $1.8 \times 10^{22}$ molecules?

The number of sodium atoms in $2$ moles of sodium ferrocyanide is

$K-40$ is a natural radioactive isotope which constitutes $0.012\%$ of natural potassium. If a cup of milk contains $370 \ mg$ of $K$,how many atoms of $K-40$ are ingested?

At $STP$,$32 \ g$ of $O_2$ contains $6.022 \times 10^{23}$ molecules. How many atoms does $32 \ g$ of sulfur $(S)$ contain under the same conditions?

At the same temperature,$10 \ dm^3$ of $N_2$ gas and $10 \ dm^3$ of gas $x$ contain the same number of molecules. What is the gas $x$?

Which of the following substances consists of a total of $1 \ mol$ of atoms? (Molar mass of $NH_3 = 17 \ g/mol, H_2O = 18 \ g/mol, N_2 = 28 \ g/mol, CO_2 = 44 \ g/mol$)