Question

The largest number of molecules is in :

• A. 36 g of water
• B. 28 g of CO
• C. 46 g of ethyl alcohol
• D. 54 g of nitrogen pentaoxide $\left(N_2{O}_5\right)$

Answer 1

Answer: (A)

36 g of water

Number of molecules present in '$W$' g of a compound $=\frac{W}{M}\times N_A$.
Here, $N_A$ represents Avogadro's number. M represents the molar mass of compound.
Number of molecules present in $36$ g of water $=\frac{36}{18}\times N_A=2N_A$
Number of molecules present in $28$ g of CO $=\frac{46}{46}\times N_A=N_A$
Number of molecules present in $46$ g of $C_2{H}_{5}OH=\frac{46}{46}\times N_A=N_A$
Number of molecules present in $54$ g of $N_2{O}_5=\frac{54}{108}\times N_A=0.5N_A$