describe the properties of alkali metals. Based on their electronic arrangement, explain whether they exist alone in nature.

1) The alkali metals are the elements found in the group 1 of the periodic table. The alkali metals are s-block elements, that is their valence electrons are located in the s orbital which can hold a maximum of 2 electrons, and are therefore, very reactive

They are called alkali metals because they form an alkaline solution when they react with water

They have to be stored under oil to keep them from reacting with air or water

Their melting point, densities, electronegativity, ionization energy are all low and they react with halogens easily to form ionic bonds

2) Based to their electronic arrangement of having their valence electrons in their s orbital, they react with other materials very readily and are not exist alone in nature but in a compound formed by combining with other elements

Explanation:

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.