Active mass of a solid is taken as ______ .

The active mass of solid is generally taken as

Active mass is defined as

Specific surface area of a solid adsorbent is the surface area of the unit mass of the adsorbent. For any adsorbent, the specific surface area may be increased by taking the adsorbent in powdered form or by increasing the pores in the solid. If unit mass of a solid, taken as cube of volume 8 cm^(3) , is powdered into identical 10^(12) cubes, then the specific surface area of the solid increased by :

Assertion (A) : The active mass of pure solid and pure liquid is taken unity. Reason (R) : The active mass of pure solids and liquids depends on the density and molecular mass. The density and molecular of a mass of pure liquids and solids are constant.

Initial active mass of a radioactive sample is 76 gm . The active mass at the end of two mean lives is approximately.

By doubling the mass of a solid body, its density becomes: