Based on the description of the demonstration, were the bubbles that formed more dense than the surround-
ing water, or less dense than the surrounding water?
F. More dense; the bubbles sank to the bottom after
formation.
G. More dense; the bubbles floated to the surface of
the beaker after formation.
H. Less dense; the bubbles sank to the bottom after
formation.
J. Less dense; the bubbles floated to the surface after
formation.

  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 transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

: )