RE-NEET 2024 Chemistry Avogadro's Law MCQ Question

Chapter: Some Basic Concepts of Chemistry — Class 11, Chapter 1 Topic: Mole Concept / Avogadro’s Law Difficulty: 🟢 Easy

✅ Ans: A — 14 g of N₂

Actually, A is not correct. The correct answer shown in your screenshot is D — 28 g of N₂.

For $1\,g$ of $H_2$:

$$\text{Moles of }H_2=\frac{1}{2}=0.5\ mol$$

Number of molecules:

$$N=0.5N_A$$

For $28\,g$ of $N_2$:

$$\text{Moles}=\frac{28}{28}=1\ mol$$

So it contains $N_A$ molecules — not equal to $0.5N_A$.

For 14 g $N_2$:

$$\frac{14}{28}=0.5\ mol$$ $$N=0.5N_A$$

Therefore:

$$\boxed{\text{Correct answer = A — 14 g of }N_2}$$

📌 NCERT: Equal number of molecules means equal number of moles. NCERT’s exemplar also calculates $1\,g\ H_2=0.5N_A$ molecules. (ncert.nic.in)

🧠 NEET Trick: Same molecules → Same moles → Compare $\frac{\text{mass}}{\text{molar mass}}$.