What overall effect does adding a catalyst have on a chemical reaction? it increases pressure on the system. it increases reactant surface area. it lowers the activation energy that is needed. it lowers the concentration of reactants.

Option (c) is the correct answer.

Explanation:

A catalyst is a substance which increases the rate of a reaction without itself getting consumed in the chemical reaction.

Activation energy is the amount of energy required by the reacting species to undergo a chemical reaction.

A catalyst lowers the activation energy that is needed for the reaction.

Before the addition of a catalyst in a chemical reaction, the particles are moving by crossing a high energy path. The particles which have low energy were not able to cross this high energy path. Therefore, this path acts as a  barrier for particles with low energy. Hence, low energy particles were not able to participate in the reaction.

On addition of a catalyst, the activation energy decreases and hence the path of reaction changes. Therefore, the particles with low energy can now cross this new energy barrier and hence, they can also participate in the reaction.

Hence, the rate of reaction will also increase.

  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-