King-post and queen-post trusses: identify the incorrect statement

Introduction / Context:
Traditional roof trusses are named for their central vertical members. Knowing how many posts each type contains is basic to selection, detailing, and measurement for roofs of different spans.

Given Data / Assumptions:

• King-post truss: classic single central post.
• Queen-post truss: two posts with a straining beam between them.
• Span suitability generally: king-post for shorter spans; queen-post for moderate spans.

Concept / Approach:
The incorrect statement is the one that says a queen-post truss has only one vertical post. By definition it has two. The other statements match standard truss descriptions and typical span guidance (though span limits vary with material and design).

Step-by-Step Solution:
Confirm king-post: one central vertical → true.Check queen-post: two verticals with straining beam → true.Identify the incorrect claim: “one vertical post” for queen-post → false.Therefore select option b as incorrect.

Verification / Alternative check:
Standard structural handbooks depict one-post and two-post configurations for king and queen trusses, respectively.

Why Other Options Are Wrong:
a and c are correct statements.d (None) is invalid because an incorrect statement exists.e is generally correct: queen-post spans exceed king-post spans in many traditional timber cases.

Common Pitfalls:
Interchanging the names; assuming “queen” implies a single larger post rather than two posts.

Final Answer:
A queen-post truss has one vertical post is the incorrect statement.