Question

The largest number of molecules is in

• A. $34g$ of water
• B. $28g$ of $C{O}_2$
• C. $46g$ of $C{H}_{3}OH$
• D. $54g$ of $N_2{O}_5$

Answer 1

Answer: (A)

(a) $34g$ of water
$\because 18g$ of $H_{2}O=6\times 10^{23}$ molecule
$\therefore 34g$ of $H_{2}O=\frac{6\times 10^{23}\times 34}{18}$
$=11.33\times 10^{23}$ molecules
(b) $28g$ of $C{O}_2$
$\because 44g$ of $C{O}_2=6\times 10^{23}$ molecules
$\therefore 28g$ of $C{O}_2=\frac{6\times 10^{23}\times 28}{44}$
$=3.8\times 10^{23}$ molecules
(c) $46g$ of $C{H}_{3}OH$
$\because 32g$ of $C{H}_{3}OH=6\times 10^{23}$ molecules
$\therefore 46g$ of $C{H}_{3}OH=\frac{6\times 10^{23}\times 46}{32}$
$=8.625\times 10^{23}$
(d) $\because 108g$ of $N_2{O}_5=6\times 10^{23}$ molecules
$\therefore 54g$ of $N_2{O}_5=\frac{6\times 10^{23}\times 54}{108}$
$=3\times 10^{23}$ molecules