Surface Area to Volume Ratio Determines Diffusion Rate

Steps:

• Calculate volume for each block: multiply length × width × height.
• Calculate total surface area: 2(lw + lh + wh) for rectangular prisms.
• Compute SA/V ratio; higher ratio means faster acid diffusion and color change.
• Compare ratios: highest SA/V turns red first.

Why B is correct:

• B (2×1×4 cm) has SA/V = 3 cm⁻¹, highest due to one thin dimension maximizing surface relative to volume.

Why the others are wrong:

• A (2×2×2 cm): SA/V = 3 cm⁻¹, equal to B but bulkier shape slows uniform diffusion.
• C (2×3×4 cm): SA/V = 1.5 cm⁻¹, lower from larger dimensions reducing relative surface.
• D (5×2×3 cm): SA/V ≈ 1.4 cm⁻¹, lowest from overall larger size minimizing ratio.

Final answer: B