A. Addition of methane to the furnace atmosphere reduces decarburising by hydrogen.
B. Nitrogen in presence of steam decar-burises high carbon steel, whereas hydrocarbon gases carburise the surface of steel at annealing temperatures.
C. Active nitrogen (formed by cracking ammonia at the metal surface) cause nitride formation with increase in surface hardness.
D. none of these.
Correct Answer
none of these.
More questions
1. Pure aniline is evaporating through a stagnant air film of 1 mm thickness at 300 K and a total pressure of 100 KPa. The vapor pressure of aniline at 300 K is 0.1 KPa. The total molar concentration under these conditions is 40.1 mole/m3 . The diffusivity of aniline in air is 0.74xl0-5m2/s.The numerical value of mass transfer co-efficient is 7.4 x 10-3. The rate of evaporation of aniline is 2.97 x 10-4. Its units are
3. Under conditions of equal reduced pressure and equal reduced temperature, substances are said to be in the 'corresponding states'. At equal reduced conditions i.e., at the corresponding state, the __________ of different gases are nearly the same.