Practice Test: Question Set - 09
1. Between 230 and 370°C, blue brittleness is caused in mild steel because of the
- (A) Immobility of dislocation
- (B) Strain-ageing
- (C) Increase in Young's modulus
- (D) Strain hardening
2. Sub zero treatment of steel is done to
- (A) Suppress martensite transformation
- (B) Enhance its working performance in sub zero atmosphere
- (C) Reduce the retained austenite in hardened steel
- (D) Induce temper brittleness after its hardening
3. The units of the rate constant for a second order reaction are
- (A) Sec-1. mole°
- (B) Moles1. sec-1
- (C) Moles-1. sec1
- (D) Moles1. sec1
4. Pick out the wrong statement about the machinability of metals. Machinability of a metal
- (A) Decreases with increase in strain hardening tendencies
- (B) Decreases with increase in hardness, in general
- (C) Depend on the composition, microstructure and physical &
mechanical properties
- (D) Decreases with increases in tensile strength & decrease in grain
size
5. The most detrimental impurity in high pressure boiler feed water is
- (A) Suspended salt
- (B) Dissolved salt
- (C) Silica
- (D) Turbidity
6. A polymer is termed as an 'elastomer', if its percentage elongation is more than 100%. An elastomer is termed as 'rubber' if its percentage elongation is more than __________ percent.
- (A) 150
- (B) 200
- (C) 300
- (D) 400
7. Biological shield in a nuclear reactor is generally provided to protect against the
- (A) α-rays
- (B) β-rays
- (C) Gamma rays & neutrons
- (D) Electrons
8. The wet bulb temperature is lower in dry air than in wet air at the same temperature. A dry bulb thermometer registers a higher temperature than a wet bulb thermometer except at _________ percent relative humidity.
- (A) 0
- (B) 100
- (C) 50
- (D) None of these
9. The thickness of oxide film is y at time t. If K1, K2 and K3 are the temperature dependent constants, the parabolic law of oxidation is given by
- (A) y2 =
2k1t + k2
- (B) y = k1 ln
(k2t + k3)
- (C) y = k1 t + k2
- (D) y = k1t3 + k2
10. Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to _________ boiling.
- (A) Film
- (B) Nucleate
- (C) Transition
- (D) All modes of
11. Plastics as a material of construction suffer from the drawback of low
- (A) Machinability
- (B) Density
- (C) Strength
- (D) Plastic deformation
12. Normalizing does not _________ of a metal.
- (A) Improve machinability & tensile strength
- (B) Remove internal stresses
- (C) Refine the structure
- (D) Remove strains caused by cold working
13. Which of the following is an ore dressing operation?
- (A) Classification
- (B) Smelting
- (C) Roasting
- (D) None of these
14. Material of construction of the electrode used in the electric resistance welding is
- (A) Stainless steel
- (B) Graphite
- (C) Copper
- (D) Steel
15. Shampoos are commercially not available in the form of
- (A) Powder
- (B) Gaseous mixture
- (C) Solution
- (D) Emulsion
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