The density of wood used for construction is in the ranges between
- A1.2 to 1.3 g/cm³
- B1.5 to 1.6 g/cm³Correct
- C2.3 to 2.6 g/cm³
- D2.6 to 2.9 g/cm³
Solution
Concept
The solid wood substance (cell wall material, without pores) has a density of about 1.5 to 1.6 g/cm³ for all species.
Step-by-step solution
1. Wood is made of cell walls (wood substance) and empty pores. 2. The density of the cell wall material alone is almost the same for all timbers, about 1.5 to 1.6 g/cm³ (specific gravity about 1.54). 3. Options C and D are stone-like values, which are far too high for wood. 4. So the answer is 1.5 to 1.6 g/cm³, option B.
Explanation
Wood substance without voids has a density of about 1.5 to 1.6 g/cm³. Real timber is lighter because of its pores, but exam books quote 1.5 to 1.6 g/cm³ for this question. So option B is correct.
Why the other options are wrong
A: 1.2 to 1.3 g/cm³ is lower than the true density of wood substance. C: 2.3 to 2.6 g/cm³ is close to concrete or stone, not wood. D: 2.6 to 2.9 g/cm³ is close to rock or aggregate, not wood.
Shortcut
Wood substance = about 1.5; stone = about 2.6.
Common mistake
Confusing the bulk density of seasoned timber (0.4 to 0.9 g/cm³) with the density of wood substance.
Correct answer: B) 1.5 to 1.6 g/cm³