Purpose of tanning in the leather industry is toa) stiffen the leatherb) smoother the leatherc)impart water resistance d) make it flexible

d) Make it flexible  

Step-by-step explanation:

Raw hides dry out to form a hard material that can decay with an offensive smell when they become wet.

Tanning converts the protein of the raw hide into a stable material that will stay flexible and not decompose when it gets wet.

a) is wrong. The purpose of tanning is to soften the leather.

b) is wrong. You smooth the leather manually with fine sandpaper.

c) is wrong. Tanning does not impart water resistance. It prevents the leather from putrefying when it does get wet.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

the answer to this question is 3.