The largest number of molecules is in

The largest number of molecules is in
  1. $36 \mathrm{~g}$ of water
  2. $28 \mathrm{~g}$ of carbon monoxide
  3. $46 \mathrm{~g}$ of ethyl alcohol
  4. $54 \mathrm{~g}$ of nitrogen pentoxide

Solution

Number of molecules in $36 \mathrm{~g}$ of water
$=\frac{36}{18} \times 6.023 \times 10^{23}=2 \times 6.023 \times 10^{23}$
Number of molecules in $28 \mathrm{~g}$ of $\mathrm{CO}$
$=\frac{28}{28} \times 6.023 \times 10^{23} \quad=1 \times 6.023 \times 10^{23}$
Number of molecules in $46 \mathrm{~g}$ of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$
$=\frac{46}{46} \times 6.023 \times 10^{23}=1 \times 6.023 \times 10^{23}$
Number of molecules in $54 \mathrm{~g}$ of $\mathrm{N}_{2} \mathrm{O}_{5}$
$=\frac{54}{108} \times 6.023 \times 10^{23}=0.5 \times 6.023 \times 10^{23}$
Hence, in these $36 \mathrm{~g}$ of water has largest number of molecules. *

Asked in: JEE-TOPICTESTS-CHEMISTRY

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