Question

Which of the following compounds has maximum number of molecules ?

• A. 2 g of \(\text{H}_{2}\)
• B. 7 g of \(\text{N}_{2}\)
• C. 8 g of \(\text{O}_{2}\)
• D. 20 g of \(\text{NO}_{2}\)

Hint:

Convert each mass to moles, because equal moles contain equal numbers of molecules.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The number of molecules is proportional to the number of moles, \(n=\dfrac{\text{mass}}{\text{molar mass}}\).

Step 2: Calculation
\(\text{H}_{2}\): \(\dfrac{2}{2}=1\) mol.
\(\text{N}_{2}\): \(\dfrac{7}{28}=0.25\) mol.
\(\text{O}_{2}\): \(\dfrac{8}{32}=0.25\) mol.
\(\text{NO}_{2}\): \(\dfrac{20}{46}\approx 0.43\) mol.

Step 3: Conclusion
2 g of \(\text{H}_{2}\) has the most moles, so it has the most molecules.

Final Answer:
2 g of hydrogen contains the maximum number of molecules. \[ \boxed{\text{(A) }\text{2 g of H}_{2}} \]