Astudent recorded the following while completing an experiment. color of substance: yellow, shiny powder effect of magnet: yellow, shiny powder was attracted the student should classify the substance as a(n)

a. element.
c. mixture.
b. compound.
d. plasma.

The answer is letter b, mixture.

Explanation:

Let's define what a mixture is at first.

Mixture- In Chemistry, mixture is a material made up of two or more different substances that are physically combined. The identities of the substances are retained. There are two types of mixture: homogenous and heterogenous.

Homogenous mixture examples: saline solution and air.

Heterogenous mixture examples: sand and oil and water.

The student's record shows the color of the substance as yellow, shiny powder. It could mean that the substance is a mixture of different kinds of powders. This is already a hint, since powder is a form of mixture. The record also shows that the substance is attracted to magnet. Part of the powder mixture contains something that is attracted to magnet. It could be an iron powder, which is the shiny one. The substance can then be classified as letter b, mixture.  

  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-