Question

Which of the following correctly represents 360 g of water?

(i) 2 moles of $H_{2}O$

(ii) 20 moles of water

(iii) $6.022\times {10}^{23}$ molecules of water

(iv) $1.2044\times {10}^{25}$ molecules of water

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

Answer 1

Answer: (B), (D)

The correct options are
B (ii)
D (iv)

(ii) 20 Moles of water = $20\times 18g=360g$ of water, because mass of 1 mole of water is the same as its molar mass i, e., 18g

(iv) $1.2044\times {10}^{25}$ molecules of water contains
$\frac{1.2044\times {10}^{25}}{N_A}$ number of moles, $N_A=6.023\times {10}^{23}$
$\therefore \frac{1.2044\times {10}^{25}}{6.022\times {10}^{23}}=20moles$
20 moles of water = $20\times 18g$
= 360 g of water