Step 1: Recall the defining chemistry and physical behaviour of sodic soils.
Sodic, or alkali, soils carry a high proportion of exchangeable sodium on the clay exchange complex, and this sodium causes the clay particles to disperse rather than flocculate, clogging the soil pores and giving these soils very poor, not high, permeability. This already shows statement A, claiming very high permeability, is false.
Step 2: Check the salt composition and pH claims.
Statement B says the salts present are dominated by sodium bicarbonates, carbonates and silicates, accurate for sodic soils and exactly why their pH runs high, typically above 8.5, so both statement B and statement C, pH greater than 8.5, are true.
Step 3: Check the electrical conductivity and exchangeable sodium criteria.
Statement D claims an electrical conductivity above 4 dS/m, but that threshold is the defining criterion for saline soils, whereas sodic soils are specifically classed by an EC below 4 dS/m alongside their high sodium, so D is false. Statement E claims an exchangeable sodium percentage of 15 percent or more, precisely the standard diagnostic threshold used to classify a soil as sodic, so E is true.
Step 4: Combine the findings.
B, C and E all correctly describe sodic soils while A and D describe the opposite behaviour or a different soil type, so only B, C and E are correct together.
\[ \boxed{(B), (C) and (E) only.} \]