23.
The diffusion co-efficient of Ni in Cu at 1000 K is 1.93 x 10-16 m2.S-1 and it is 1.94 × 10-14 m2.S-1 at 1200 K. The activation energy (in k.J.mole-1) for the diffusion of Ni in Cu is

26.
'Sterilised zone' around a hazardous chemical industry is an area with __________ km radius around it, in which the total population/inhabitants should be less than 20000 preferably in the upwind direction.

29.
All modes of heat transfer i.e., conduction, convection & radiation occur in case of the