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Basic Civil Engineering Multiple Choice Questions on “Classification of Timber”.
1. Trees are generally classified, based on the mode of growth into:
a) 2
b) 6
c) 4
d) 3
Answer: a
Clarification: The two types are endogenous (inward growth) and exogenous (outward growth).
2. What is the life time of a moderately durable timber?
a) 10-20 years
b) 1-5 years
c) 10-15 years
d) 5-10 years
Answer: d
Clarification: The life time of high durability timber is more than 10 years, for moderately it is between 5-10 years and for low, it is less than 5 years.
3. Which of the following is an example of soft wood?
a) Sal
b) Oak
c) Deodar
d) Mahogany
Answer: c
Clarification: Sal, Oak and Mahogany are all examples of hard wood.
4. Which IS Code gives a classification of commercial timbers and their zonal distribution?
a) IS 620
b) IS 399
c) IS 401
d) IS 190
Answer: b
Clarification: IS 620 gives details about wooden tools handles. IS 401 specifies about the preservation of timber and IS 190 about coniferous sawn timber.
5. IS 3629-1966 classifies timber into 3 classes based on:
a) Availability
b) Average life
c) Durability
d) Density
Answer: b
Clarification: There are 3 classes-class I, class II and class III. Class I timber has an average life of 120 months or more, Class II of 60 months or over, but less than 120 months. Class III has an average life of less than 60 months.
6. Which of the following is a type of non-refractory timber?
a) Semul
b) Teak
c) Sheesham
d) Sal
Answer: a
Clarification: Bases on seasoning, timber has been classified into non-refractory, moderately refractory and eminent refractory timber. Teak and Sheesham are examples of moderately refractory and Sal of eminent refractory timber.
7. Which of the below type of timber has Young’s Modulus greater than 9800 N/mm2, but less than 12600 N/mm2?
a) Average timber
b) Very good timber
c) Good timber
d) Light timber
Answer: c
Clarification: Average timber has Young’s Modulus (E) varying between 6600 N/mm2 and 9800 N/mm2. Very good timber has E greater than 12600 N/mm2. There is no classification as light timber based on E.
8. What is the density of a light timber?
a) 5.5 kN/m3
b) Less than 2.5 kN/m3
c) 2.5 kN/m3
d) Less than 5.5 kN/m3
Answer: d
Clarification: Density of light to very light timber is less than 5.5 kN/m3. Moderate timber has density between 5.5 and 7.5 kN/m3 and heavy to very heavy timber has density greater than 7.5 kN/m3.
9. Hard wood is strong in tension and weak in compression.
a) True
b) False
Answer: b
Clarification: Soft wood is strong in tension and weak in compression. Hard wood is equally strong in tension and compression.
10. Exogenous trees are further divided into:
a) 3
b) 4
c) 2
d) 5
Answer: c
Clarification: Exogenous trees are those in which trees grow outward. The 2 types are coniferous (evergreens) and deciduous (broad leaf) trees.
11. Which of the below is a property of soft wood?
a) Medullary rays are less distinct
b) Annual rings are less distinct
c) Dark in colour
d) Close grained structure
Answer: a
Clarification: The other 3 options are properties of hard wood. Soft wood is light in colour, annual rings are clearly visible and it has resinous structure.