Question

The largest number of molecules is in

• A. $34 \,g$ of water
• B. $28 \,g$ of $ CO_{2} $
• C. $46 \,g$ of $ CH_{3}OH $
• D. $54 \,g$ of $ N_{2}O_{5} $

Answer 1

Answer: (A)

(a) $34\, g$ of water
$\because 18 \,g$ of $H _{2} O =6 \times 10^{23}$ molecule
$\therefore 34\, g$ of $H _{2} O =\frac{6 \times 10^{23} \times 34}{18}$
$=11.33 \times 10^{23}$ molecules
(b) $28\, g$ of $CO _{2}$
$\because 44 \,g$ of $CO _{2}=6 \times 10^{23}$ molecules
$\therefore 28\, g$ of $CO _{2}=\frac{6 \times 10^{23} \times 28}{44}$
$=3.8 \times 10^{23}$ molecules
(c) $46\, g$ of $CH _{3} OH$
$\because 32\, g$ of $CH _{3} OH =6 \times 10^{23}$ molecules
$\therefore 46\, g$ of $CH _{3} OH =\frac{6 \times 10^{23} \times 46}{32}$
$=8.625 \times 10^{23}$
(d) $\because 108\, g$ of $N _{2} O _{5}=6 \times 10^{23}$ molecules
$\therefore 54\, g $ of $ N _{2} O _{5} =\frac{6 \times 10^{23} \times 54}{108}$
$=3 \times 10^{23} $ molecules