Which from following substances consists of total 1 mole atoms in it? (Molar mass of $\left.\mathrm{NH}_3=17…

Which from following substances consists of total 1 mole atoms in it? (Molar mass of $\left.\mathrm{NH}_3=17, \mathrm{H}_2 \mathrm{O}=18, \mathrm{~N}_2=28, \mathrm{CO}_2=44\right)$
  1. $4.25 \mathrm{~g} \mathrm{NH}_3$
  2. $1.8 \mathrm{~g} \mathrm{H}_2 \mathrm{O}$
  3. $2.8 \mathrm{~g} \mathrm{~N}_2$
  4. $4.4 \mathrm{~g} \mathrm{CO}_2$

Solution

$\begin{aligned} 4.25 \mathrm{~g} \mathrm{NH}_3 & =\frac{4.25}{17} \mathrm{~mol} \mathrm{NH}_3 \\ & =0.25 \mathrm{~mol} \mathrm{NH}_3 \\ & 1 \mathrm{~mol} \mathrm{NH}_3=1 \mathrm{~mol} \mathrm{~N} \text {-atoms }+3 \mathrm{~mol} \mathrm{H} \text {-atoms } \\ \therefore \quad 0.25 \mathrm{~mol} \mathrm{NH}_3 & =0.25 \times 4 \\ & =1 \mathrm{~mol} \text { atoms }\end{aligned}$

Asked in: MHT CET 2023 (11 May Shift 2)

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