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?

Related Mcqs:

1. In “Imperial Smelting Process” for extraction of zinc, zinc vapour thus produced is quenched in the external condenser by the use of the following _______________________?

   A. Jet of water at high pressure
   B. Blast of air
   C. Mixture of water and air
   D. Rain of molten lead

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

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

3. _____________ 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

4. The boiling & freezing points on a newly defined temperature scale in degree ‘D’ are 400°D & 100°D respectively. The temperature reading corresponding to 60°C on this new temperature scale will be equal to _____________ °D ?

   A. 140
   B. 180
   C. 240
   D. 280

5. Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called_______________________?

   A. Tempering
   B. Hardening
   C. Annealing
   D. Normalising

6. The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K) ?

   A. T
   B. 1/T
   C. T2
   D. 1/T2

7. Minimum temperature upto which water can be theoretically cooled down in the cooling tower by evaporative cooling is equal to the ______________ temperature of air?

   A. Wet bulb
   B. Dry bulb
   C. Saturation
   D. Dew point

8. The minimum temperature to which the water can be cooled in a cooling tower is the ______________ temperature of air?

   A. Ambient
   B. Dry bulb
   C. Dew point
   D. Wet bulb

9. A gas which is collected over water becomes moistened due to water vapor, exerts its own partial pressure at the gas temperature, which is termed as its_______________?

   A. Aqueous tension
   B. Saturated humidity
   C. Vapor pressure
   D. Absolute humidity

10. 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%.