Metallurgical Problems Mid - I, September - 2014

1.The quantity of heat flowing through a conductor is proportional to its:
  • Cross sectional area
  • length
  • Temperature
  • Coefficient of thermal expansion
Answer: A
2.Water boils at lower temperature at mountain altitudes than sea level because:
  • of low air temperature
  • of low air pressure
  • of low density of water
  • of impurities in water
Answer: B
3.In which of the following minerals, aluminum is not present
  • Fluorspar
  • Cryolite
  • Feldspar
  • Mica
Answer: A
4.The process in which metal oxide is reduced to metal by aluminum is called
  • Smelting
  • aluminothermy
  • hydrothermy
  • no specific name
Answer: B
5.Two vessels made of different metals are similar in shape and dimensions. They are filled with ice at 0oC. due to absorption of heat from outside, in one vessel (thermal conductivity K1) ice melts in 25 minutes. While in another (K2) ice melts in 20 minutes. The ratio K1/K2 is.
  • 0.8
  • 1.25
  • 12.5
  • 0.08
Answer: A
6.The temperature of a body is 90oC. Its temperature in Fahrenheit is given by:-
  • 19.4
  • 124
  • 164
  • 194
Answer: D
7.On heating, the density of a solid generally:-
  • increases
  • decreases
  • remains constant
  • Increase and decrease are equality possible depending upon the substance being considered
Answer: B
8.Which of the following metals can be extracted by smelting
  • Aluminum
  • Magnesium
  • Iron
  • None of these.
Answer: C
9.In parabolic rate of oxidation, the oxide thickness is proportional to
  • t1/2
  • t
  • t2
  • t3
Answer: A
10.For a protective oxide layer to form, the ratio of the volume of oxide formed to that of metal consumed should be
  • < 1
  • 1
  • > 1
  • >> 1
Answer: C
11.Aluminum is obtained from Al2O3 by _______________reduction.
Answer: Electrolytic
12.In the metallurgical process for electro refining of the metal, the anode is made of ____________________metal.
Answer: Impure
13.Slag is a product formed during smelting by combination of ____________and impurities.
Answer: Flux
14.______________metal is extracted by zone refining.
Answer: Zinc
15.The most abundant metal in earth’s crust is ________________________
Answer: Aluminum
16.The purification of crude metal is referred to as ___________________________
Answer: Refining
17.The band gap of CdS is 2.45ev; the wave length that will observe on incidence of visible light is_____________________.
Answer: 5058 A0
18.The process of removal of gaunge from ore is known as ______________________
Answer: Concentration
19.For a first order chemical reaction the concentration of the reactant decreases`___________.
Answer: Linearly with time
20.For a Spontaneous, natural process at constant temperature and pressure the free energy of the system always___________________.
Answer: Increases