Question

Which of the following contains maximum number of molecules?

• A. \(0.4\) g \(\text{H}_2\) gas
• B. \(3.2\) g of \(\text{O}_2\) gas
• C. \(16.8\text{ dm}^3\) of \(\text{H}_2\) gas at STP
• D. \(11.2\text{ dm}^3\) of \(\text{O}_2\) gas at STP

Hint:

Convert each sample to moles; the largest number of moles has the most molecules.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The number of molecules is proportional to the number of moles, \(N = n N_A\).

Step 2: Find moles:
A: \(\frac{0.4}{2} = 0.2\) mol of \(\text{H}_2\).
B: \(\frac{3.2}{32} = 0.1\) mol of \(\text{O}_2\).
C: \(\frac{16.8}{22.4} = 0.75\) mol of \(\text{H}_2\) at STP.
D: \(\frac{11.2}{22.4} = 0.5\) mol of \(\text{O}_2\) at STP.

Step 3: Compare:
\(0.75 > 0.5 > 0.2 > 0.1\), so C has the most molecules.

Final Answer:
Sample C has the most molecules, option (C). \[ \boxed{16.8\ \text{dm}^3\ \text{of H}_2\ \text{at STP}} \]