RRB JE exam Civil Engineering Building Materials Important MCQs – 4

31. The disease of dry rot in timber is caused by
a) lack of ventilation
b) alternate wet and dry conditions
c) complete submergence in water
d) none of the above
Correct Option: a

32.​​ Plywood has the advantage of'
a) greater tensile strength in longer direction
b) greater tensile strength in shorter direction
c) same tensile strength in all directions
d) none of the above
Correct Option: c

33. In which of the following directions, the​​ strength of timber is maximum ?
a) parallel to grains
b) 45° to grains
c) perpendicular to grains
d) same in all directions
Correct Option: a

34. The moisture content in a well seasoned timber is
a) 4% to 6%
b) 10% to 12%
c) 15% to 20%
d) 100% 
Correct Option: b

35. The trunk of tree left after cutting all the branches is known as
a) log
b) batten
c) plank
d) baulk
Correct Option: a

36. The age of a tree can be known by examining
a) cambium layer
b) annular rings
c) medullary rays
d) heart wood
Correct Option: b

37. Plywood is made by bonding together thin layers of wood in such a way that the angle between grains of any layer to grains of adjacent layers is
a) 0°
b) 30°
c) 45°
d) 90°
 Correct Option: d

38. The plywood
a) has good strength along the panel only
b) can be spilt in the plane of the panel
c) has greater impact resistance to blows than ordinary wood
d) cannot be bent more easily than ordinary wood of same thickness
Correct Option: c

39. The practical limit of moisture content achieved in air drying of timber is
a) 5%
b) 15%
c) 25%
d) 35%
Correct Option: b

40. First class timber has an average life of
a) less than one year
b) 1 to 5 years
c) 5 to 10 years
d) more than 10 years
Correct Option: d