Permanent magnets are made of high carbon steel and
15% of cobalt
20% of cobalt
35% of cobalt
45% of cobalt
Correct Answer :
D. 45% of cobalt
Related Questions
Quick lime
Generates heat when added to water
Reacts with carbon dioxide
May be used for white-washing
All the above
Percentage of carbon content in mild steel is
Less than 0.25
Between 0.25 and 0.7
Between 0.7 and 1.5
Greater than 1.5
Cement paints usually
Contain hydrated lime
Contain 5% to 10% colour pigments
Contain 5% sodium chloride
All the above
Gypsum is a
Mechanically formed sedimentary rock
Igneous rock
Chemically precipitated sedimentary rock
Metamorphic rock
The yield strength and tensile strength of low carbon steel may be improved by the addition of
Manganese
Chromium
Nickel
Vanadium
For a 50 kg cement bag water required, is
16.5 litres
18.5 litres
20.5 litres
22.5 litres
The presence of sand in brick earth prevents:
Cracking of bricks
Shrinkage of bricks
Warping of bricks
None of these
The steel used for rails under heavy traffic and on sharp curves, is
Nickel steel
Chrome steel
Manganese steel
Vanadium steel
In arches, stratified stones are placed so that their planes are
Parallel
Perpendicular
Radial
None of these
The steel which contains fissures and cavities, is manufactured by
Cementation process
Crucible process
Bessemer process
Open hearth process
The compound of Portland cement which reacts immediately with water and also sets first is
Tri-calcium silicate
Di-calcium silicate
Tri-calcium aluminate
Tetra calcium alumino ferrite
The frog of the brick in a brick masonry is generally kept on
Bottom face
Top face
Shorter side
Longer side
The most common admixture which is used to accelerate the initial set of concrete is
Gypsum
Calcium chloride
Calcium carbonate
None of the above
Pick up the correct statement from the following:
Acid test is done to find out the weathering quality of stones
Attrition test is done to find out the rate of wear of stones which are used in road construction
Crushing test is done to find out the compressive strength of the stone
All the above
Portland pozzolana cement possesses
Higher resistance to chemical attack
Lower heat of hydration
Lower shrinkage on drying
All the above
Bessemer process is used for the manufacture of
Pig iron
Cast iron
Wrought iron
Steel
Sapwood consists of
Innermost annular rings around the pith
Portion of timber between heartwood and cambium layer
Thin layers below the bark
Thin fibre which extends from the pith outwards and holds the annular rings together
Elastomers can extend upto
Five times their original dimensions
Seven times their original dimensions
Ten times their original dimensions
Three times their original dimensions
The usual percentages of clay and metal in cermet are:
50%, 50%
60%, 40%
70%, 30%
80%, 20%
The practical limit of moisture content achieved in air drying of timber is
5 %
15 %
25 %
35 %
Early attainment of strength in rapid hardening cement is mainly due to
Gypsum
Finer grinding
Tri-calcium silicate
Tri-calcium aluminate
Which one of the following is an air binding material?
Gypsum
Acid-resistant cement
Quick lime
All of these
Pick up the correct statement from the following:
Plastics have generally low melting point
The coefficient of thermal expansion of plastics is about three times than that of steel
The acoustical boards prepared by impregnating fibre-glass with phenolic resins has absorption coefficient of about 0.67
All the above
The proportions of lime and sand in the mortar normally used in brick construction are
1 : 2
1 : 4
1 : 6
1 : 8
For construction of structures under water, the type of lime used, is
Hydraulic lime
Fat lime
Quick lime
Pure lime
Plywood is made from
Common timber
Bamboo fibre
Teak wood only
Asbestos sheets
Which of the following timbers is suitable for making sports goods?
Mulberry
Mahogany
Sal
Deodar
Pick up the correct statement from the following:
Adding 5% to 6% of moisture content by weight, increases the volume of dry sand from 18% to 38%
The bulking of fine sand is more than that of coarse sand
If the percentage content of moisture exceeds 10%, increase in bulk of sand starts increasing
All the above
The cracks which extend from bark towards the sap wood in the cross section of a tree, are called
Radial shakes
Star shakes
Heart shakes
Cup shakes
Compared to mild steel, cast iron has (i) High compressive strength (ii) High tensile strength (iii) Low compressive strength (iv) Low tensile strength The correct answer is
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)