Electrolytic reduction cell used for conversion of calcined Al2O3 to Al is a carbon lined furnace operating at 800-900 °C. The purpose of electric current supplied to the furnace is to___________________?

Related Mcqs:

1. The Al2O3 content of cryolite in Hall-Heroult cell is maintained between _______________ percent ?

   A. 2-5
   B. 18-20
   C. 12-15
   D. 6-12

2. The refractory lining of the bottom in a basic electric arc furnace is made of___________________?

   A. Silica
   B. Alumina
   C. Magnesia
   D. Fireclay

3. The usual energy consumption in electric arc furnace steel making is _____________ KWh/ton of steel ?

   A. 60 – 100
   B. 400 – 700
   C. 1200 -1500
   D. 2000 – 2300

4. For efficient performance of a blast furnace, the extent of reduction of Wustite (FeO) should be___________________?

   A. 100% indirect reduction
   B. 100% direct reduction
   C. 50-60% indirect reduction
   D. 30-40% indirect reduction

5. One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is____________________?

   A. 100
   B. 900
   C. 9000
   D. 10000

6. Which of the following metals is not subjected to electrolytic refining/purification ?

   A. Copper
   B. Zinc
   C. Tin
   D. Aluminium

7. Which of the following are made out of the carbon steel having carbon content of 0.9 to 1%?

   A. Small punches, broaches reamers and springs
   B. Cutlery, screws, rivets and files
   C. Mandrels, twist drills, small lathe tools and razors
   D. Forgings like can shaft, structural steel plate, threading dies and drawing dies

8. The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by (T1 – T2)/T1. The co-efficient of performance (CO.P.) of a Carnot heat pump operating between T1 and T2 is given by_________________?

   A. T1/(T1-T2)
   B. T2/(T1-T2)
   C. T1/T2
   D. T2/T1

9. A semi-conductor is damaged & behaves like a conductor, on passing a strong electric current through it, because it heats up the crystals & breaks the covalent bonds resulting in _______________ electrons ?

   A. Lack of free
   B. Excess of
   C. Decrease in
   D. None of these

10. Energy to be supplied to the radioactive nucleus for the emission of a neutron is ________________ MeV?

    A. 0.8
    B. 7.8
    C. 200
    D. 10000