Total number of atoms represented by the compound $CuSO_4 \cdot 5H_2O$ is

The mass of $1$ mole of electrons is .......

Find the maximum number of atoms in the following:
$(i)$ $1 \ g$ $Au_{(s)}$
$(ii)$ $1 \ g$ $Na_{(s)}$
$(iii)$ $1 \ g$ $Li_{(s)}$
$(iv)$ $1 \ g$ $Cl_{2(g)}$

The number of electrons in $2.1 \ g$-ion of $Cl^{-}$ is

Containers $A, B$,and $C$ of equal volume contain oxygen,neon,and methane gases respectively at the same temperature and pressure. Which of the following is the correct order of their increasing mass?

How many water molecules are there in one drop of water $($Volume $= 0.0018 \ mL)$ at room temperature?