Question

Which of the following correctly represents $180\, g$ of water?
(i) $5$ moles of water
(ii) $10$ moles of water
(iii) $6.023 \times 10^{23}$ molecules of water
(iv) $6.023 \times 10^{24}$ molecules of water

• A. (i) and (ii)
• B. (i) and (iv)
• C. (ii) and (iv)
• D. (ii) and (iii)

Answer 1

Answer: (C)

$18 \,g$ of $H_{2}O =1$ mol
$180\, g$ of $H_{2}O = 10$ mol
$18\, g$ of $H_{2}O = 6.023\times 10^{23}$ molecules of $H_{2}O$
$180\, g$ of $H_{2}O =\frac {6.023\times 10^{23}}{18} \times 180$
$= 6.023\times 10^{24}$ molecules of $H_{2}O$