Step 1: Analyze each compound - Compound 1 (−OCH3 group attached): The −OCH3 group exhibits both inductive (−I) and mesomeric (+M) effects. However, hyperconjugation is not applicable here. Not included.
Step 2: Final Count From the analysis, only 4 compounds exhibit all three effects: inductive, mesomeric, and hyperconjugation.
Final Answer: 4.
In a resonance tube closed at one end. Resonance is obtained at lengths \( l_1 = 120 \, \text{cm} \) and \( l_2 = 200 \, \text{cm} \). If \( v_s = 340 \, \text{m/s} \), find the frequency of sound.
Relative stability of the contributing structures is :
Match List-I with List-II: List-I