Aluminium is extracted from____________________?

Related Mcqs:

1. Titanium is added to molten aluminium alloys before casting for the purpose of_____________________?

   A. Grain refinement
   B. Increasing corrosion resistance
   C. Reducing porosity
   D. Improving fluidity

2. The most important requirement for aluminium industry is the availability of cheap _______________?

   A. Ore
   B. Electrical power
   C. Labour
   D. Abundant water

3. Hot extrusion of aluminium is done in the temperature range of ________________ °C ?

   A. 550-600
   B. 450-500
   C. 350-400
   D. 250-300

4. A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about ____________________ °C?

   A. 370
   B. 340
   C. 320
   D. 300

5. _____________ is the process of coating the surface of steel with aluminium oxide, thereby imparting it increased resistance to corrosion & oxidation upto a temperature of 700°C ?

   A. Veneering
   B. Galvanising
   C. Electroplating
   D. Calorising

6. Identify the correct statement with reference to the extractive metallurgy of aluminium ?

   A. The electrolyte consists of molten Na3AlF6 with approximately 1 to 8% Al2O3
   B. Approximately 80% of the aluminium deposited on the cathode comes from cryolite
   C. Sodium is deposited along with aluminium, but is immediately vaporised
   D. Anode effect sets in when the cryolite concentration goes below 40%.

7. Name the safety device used to protect the boiler, when the water level falls below a minimum level ?

   A. Blow down valve
   B. Blow off cock
   C. Fusible plug
   D. Safety valve

8. Consumable electrodes are used in the ____________________ welding?

   A. Gas
   B. Arc
   C. Thermit
   D. Resistance

9. The diffusion co-efficient of Ni in Cu at 1000 K is 1.93 × 10-16 m2S-1 and it is 1.94 × 10-14 m2S- 1 at 1200 K. The activation energy (in k. J.mole-1) for the diffusion of Ni in Cu is_________________?

   A. 130
   B. 180
   C. 230
   D. 250

10. The life of a ball bearing is inversely proportional to________________?

    A. (Load)1
    B. (Load)2
    C. (Load)3
    D. (Load)0.33