In a pressure vessel containing multiple openings of various dimensions at different parts, stress concentration at the edges of the opening is maximum which becomes negligibly small beyond the area covered by __________ times the hole diameter.

A. $$\frac{1}{8}$$ and $$\frac{1}{{64}}$$ B. $$\frac{1}{{64}}$$ and $$\frac{1}{8}$$ C. $$\frac{1}{2}$$ and 8 D. $$\frac{1}{2}$$ and 5

A. Less than B. 1.25-1.50 times C. 2.5 times D. One-fourth of

A. Laminar flow B. Complete back mixing C. Plug flow D. Eddy diffusivity = 0

A. 5 B. 15 C. 7.5 D. 50