The number of water molecules present in a drop of water weighing $0.018 \ g$ is

Number of molecules in $100 \ mL$ of each of $O_2$,$NH_3$,and $CO_2$ at $STP$ are

In a sample of $CaCO_3$,there are $3.01 \times 10^{23}$ ions of $Ca^{+2}$ and an equal number of $CO_3^{-2}$ ions. The mass of the sample is = $......$ grams.

In which case is the number of molecules of water maximum?

Which of the following contains $6.02 \times 10^{22}$ molecules?

Assertion $(A)$: Equal moles of different substances contain the same number of constituent particles.
Reason $(R)$: Equal weights of different substances contain the same number of constituent particles.
The correct answer is