521. Nitriding of steel is a process for________________?
A. Case hardening
B. Spheroidising
C. Normalising
D. Annealing

522. As the impurities are oxidised, the melting point of iron___________________?
A. Decreases
B. Remains unchanged
C. Increases
D. May increase or decrease; unpredictable

523. Wrought iron is having very high ________________?
A. Hardness
B. Strength
C. Corrosion resistance
D. Susceptibility to changes in its properties by heat treatment

524. A hardness depth of about 3 mm can be achieved by induction hardness in ______________ seconds?
A. 5
B. 100
C. 250
D. 500

525. Presence of cobalt in steel improves its____________________?
A. Cutting ability
B. Corrosion resistance
C. Tensile strength
D. None of these

526. Bush bearings are made of______________________?
A. Mild steel
B. Phosphorous bronze
C. White metal alloys
D. None of these

527. How many atoms are there per unit cell in a body centred cubic lattice system ?
A. 6
B. 5
C. 3
D. 2

528. Nickel base alloys with ______________ are known as monel metal?
A. Zinc
B. Tin
C. Copper
D. Molybdenum

529. Glass is corroded by________________?
A. Fluorine (dry or wet)
B. Sulphuric acid
C. Phosphoric acid
D. None of these

530. Tin base and lead base alloys are used for bearing materials. Tin compared to lead has lower_________________?
A. Price
B. Corrosion resistance
C. Thermal conductivity
D. Abundant availability

NOTE
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