581. Which of the following comprises of hydrocarbons ?
A. Mica flakes
B. Glass
C. Rubber
D. None of these

582. The softest material just next to talc in the Mho’s scale is___________________?
A. Quartz
B. Gypsum
C. Feldspar
D. Fluorite

583. ‘Age hardening’ of duralumin is due to____________________?
A. Copper
B. Magnesium
C. Both A. & B.
D. Neither A. nor B.

584. In cold working of metal as compared to its hot working____________________?
A. Cracks and blow holes are eliminated
B. Ductility and impact strength improves
C. Appreciable strain hardening is produced
D. Yield stress, hardness and fatigue strength is not at all affected

585. Spark plugs are made of______________________?
A. High alumina ceramic
B. Metallic carbides
C. Corundum
D. Carborundum

586. The crystal structure of most of the common metals is_____________________?
A. Orthorhombic
B. Cubic
C. Hexagonal
D. None of these

587. Cast iron is having very high ___________________?
A. Proximity between its elastic limit and ultimate breaking strength
B. Ductility
C. Tensile strength
D. All A., B. and C.

588. Failure of a material is termed as fatigue failure, if it fails below the yield point. The resistance to fatigue failure of a material is measured by the__________________?
A. Ultimate tensile strength (U.T.S.)
B. Endurance limit
C. Elastic limit
D. None of these

589. ____________ does not change during phase transformation processes like sublimation, melting & vaporisation?
A. Entropy
B. Gibbs free energy
C. Internal energy
D. All (A), B. & (C)

590. At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is____________________?
A. Zero
B. One
C. Infinity
D. Negative

NOTE
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