The gas SF6 is used to trace air flows because it is non-toxic and can be detected selectively in air at a concentration of 1.0 ppb. What partial pressure is this? At this concentration, how many molecules of SF6 are contained in 1.0 cm3 of air at T = 46 °C

  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-

35. a insulated cylinder of solid gold (k 310 kw/m-k) of radius v2 m and height 5 m is heated at one end until the temperature at each point in the cylinder is given by w(r, y, z) (30 z2)(2-(r2+ y2). determine the rate of heat flow across each horizontal disk given by z 1, z 2, and z 3, identifying which has the greatest rate of heat flow across it.

explanation: