Which sample contains the maximum number of molecules

1. A.
   $0.4$ g $\mathrm{H_2}$ gas
2. B.
   $3.2$ g of $\mathrm{O_2}$ gas
3. C.
   $16.8\ \mathrm{dm^3}$ of $\mathrm{H_2}$ gas at STP
4. D.
   $11.2\ \mathrm{dm^3}$ of $\mathrm{O_2}$ gas at STP

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1. A.
   $18$ mL of water
2. B.
   $10^{-3}$ mol of water
3. C.
   $0.18$ g of water
4. D.
   $0.00224$ L of water vapour at $1$ atmp. and $273$K

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