Question

Calculate the mass of water which contains the same number of molecules as that of 667.5 g of aluminium chloride.

• A. 90 g
• B. 72 g
• C. 54 g
• D. 108 g

Answer 1

The correct option is A 90 g

133.5g of $AlC{l}_3$ contains = $6.02\times {10}^{23}$ molecules
667.5g of $AlC{l}_3$ contains = $\frac{6.02\times {10}^{23}}{133.5}\times 667.5$ = $30.1\times {10}^{23}$
Now mass of $6.02\times {10}^{23}$ molecules of $H_{2}O$ = 18g
mass of $30.1\times {10}^{23}$ molecules of $H_{2}O$ = $\frac{18}{6.02\times {10}^{23}}\times 30.1\times {10}^{23}$ = 90g