Diffusion co-efficient of a metal in a solid solution depends upon its ?

Related Mcqs:

1. 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

2. Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting) ?

   A. V/A
   B. V/A2
   C. V2/A
   D. V2/A2

3. The two elements required to form substitutional solid solution should not have___________________?

   A. Same crystalline structure
   B. Same valency
   C. Widely differing electronegativity
   D. Same atomic sizes

4. What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively ?

   A. 2
   B. 8
   C. 10
   D. 40

5. The concentration of (H+) ions is 4 x 10-5 in a solution. Then pH of the solution will be (Given log 4 = 0.6) ?

   A. 4.4
   B. 5.6
   C. 8.4
   D. 2.4

6. The activity co-efficient of the solute in a dilute solution ?

   A. Decreases with the increase of concentration of the solute
   B. Increases with the increase of concentration of the solute
   C. Remains constant
   D. Is unity at infinite dilution

7. If a solid is compressed adiabatically in its elastic range, its _____________ remains constant ?

   A. Internal energy
   B. Enthalpy
   C. Entropy
   D. Temperature

8. The softness or hardness of a grinding wheel depends upon the type & amount of bonding material used. For general purpose cutter grinding _______________ grinding wheel is normally used ?

   A. Hard
   B. Soft
   C. Silicon carbide
   D. Aluminium oxide

9. Maximum hardenability of steel depends upon its_______________________?

   A. Chemical composition
   B. Carbon content
   C. Grain size
   D. Alloying elements content

10. Internal energy of a gas obeying Van-Der-Waals equation of state, [p + (a/v2)] (V – b) = RT, depends upon its___________________?

    A. Pressure & temperature
    B. Pressure & specific volume
    C. Temperature & specific volume
    D. Temperature only