Calculate the number of moles present in $9.10 \times 10^{-2} \ kg$ of water.

The number of moles of $BaCO_3$ which contain $1.5$ moles of oxygen atoms is:

$5.6 \, L$ of oxygen at $STP$ contains .............

Which has the maximum number of molecules?

Calculate the following for $3 \ mol$ of ethane $(C_2H_6)$:
$(i)$ Number of moles of carbon atoms
$(ii)$ Number of moles of hydrogen atoms
$(iii)$ Number of molecules of ethane

$A$ sample of ammonium phosphate,$(NH_4)_3PO_4$,contains $6$ moles of hydrogen atoms. The number of moles of oxygen atoms in the sample is: