$\,{\rm{1}}{{\rm{0}}^{{\rm{ - 3}}}}\,{\rm{mol}}\,\,{\rm{of}}\,{\rm{water}}$

${\rm{18}}\,{\rm{mL}}\,{\rm{of}}\,{\rm{water}}$

$\,{\rm{0}}{\rm{.00224}}\,{\rm{L}}\,\,{\rm{of}}\,{\rm{water}}\,{\rm{vapours}}\,\,{\rm{at 1 atm }}\,{\rm{and }}\,{\rm{273}}\,\,{\rm{K}}$

${\rm{0}}{\rm{.18}}\,\,{\rm{g}}\,\,{\rm{of}}\,\,{\rm{water}}$

$7.22 imes {10^{24}}$ atoms

$7.22 imes {10^{23}}$ atoms

$7.22 imes {10^{25}}$ atoms

All of these

$26.9 imes {10^{18}}$ molecules

$2.69 imes {10^{19}}$ molecules

$2.69 imes {10^{18}}$ molecules

$26.9 imes {10^{19}}$ molecules

20

40

60

80

$4{\rm{g}}\;{\rm{of}}{\mkern 1mu} \;{{\rm{H}}_2}{\rm{O}}$

$2{\rm{g}}\;{\rm{of}}\;{\rm{marsh}}\;{\rm{gas}}$

4{\rm{g}}\;{\rm{of}}{\mkern 1mu}  \;{\rm{PC}}{{\rm{l}}_5}

$2{\rm{g}}\;{\rm{of}}\;{\rm{phosgene}}$

18 g

$1.8 imes 10^{-8}$ g

$18 imes 10^{15}$ g

Cannot be determined

Twice that in 60 g carbon

$6.023 imes {10^{22}}$

Half in 8 gr of He

$558.5 imes 6.023 imes {10^{23}}$

A = 10, B = 80

A = 30, B = 40

A = 20, B = 60

A = 40, B = 20

0.00224 L of water vapours at 1 atm and 273 K

0.18 g of water

18 ml of water

10⁻³ mol of water

$I,{\rm{ }}II,{\rm{ }}III$

$II,{\rm{ }}III,{\rm{ }}IV$

$I,{\rm{ }}II,{\rm{ }}IV$

$II,{\rm{ }}I$

Same proton number

Same electronic configuration

Same electron number

Same size