Which of the following observations indicates that atoms of all elements contain small, negatively charged particles? Alpha particles are repelled by cathode rays of elements. Cathode rays are deflected towards a positively charged rod. A particular frequency of light is produced by a gas in an excited state. Certain areas of the atom called orbitals contain all the charged particles.

The correct option is;

Cathode rays are deflected towards a positively charged rod

Explanation:

Cathode rays are  beam of electrons emitted from the cathode in a vacuum tube and moving towards the anode, due to the difference in the voltage between the electrodes

The discovery of the electrons was through the proof by Thomson that cathode rays were a negatively charged, previously unknown particle, which was to become known as the electron.

a plasma is a warm ionized gasoline consisting of approximately equal numbers of definitely charged ions and negatively charged electrons. the characteristics of plasmas are notably unique from the ones of ordinary neutral gases in order that plasmas are considered a awesome "fourth kingdom of remember."

  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-