How does the atomic radius of an element is related to its metallic character

The large the atomic radius the more the metallic character of elements

Explanation:

The atomic radius is related to the metallic character in a way that the larger the atomic radius, the more metallic a body becomes.

Therefore, as we go down a group, metallic character increases.

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.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.