Question

How many fundamental vibrational modes are present in the $H_{2}S$ molecule}

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

Non-linear: $3n-6$; Linear: $3n-5$.

Answer 1

The Correct Option is C

Step 1: Concept
The number of fundamental vibrational modes for a molecule depends on its atomicity and geometry (linear vs. non-linear).

Step 2: Meaning
For a non-linear molecule with $n$ atoms, the formula is $3n - 6$.

Step 3: Analysis
$H_{2}S$ is a non-linear (bent) molecule consisting of 3 atoms ($n=3$). Calculation: $(3 \times 3) - 6 = 9 - 6 = 3$.

Step 4: Conclusion
There are 3 fundamental vibrational modes (symmetric stretching, asymmetric stretching, and scissoring/bending). Final Answer: (C)