The permissible compressive strength of M-20 concrete grade is:

A. 100 kg/cm²

B. 150 kg/cm²

C. 200 kg/cm²

D. 250 kg/cm²

Correct Answer: C. 200 kg/cm²

📊 M-20 Strength in kg/cm²

Step 1. M20 → f_ck = 20 N/mm²

Step 2. Convert to kg/cm²:20 N/mm² × 10.2 = 204 kg/cm² ≈ 200 kg/cm²

M-20 permissible compressive strength ≈ 200 kg/cm² — option C.

Rule of thumb: M-grade × 10 = kg/cm². M15→150, M20→200, M25→250, M30→300.