Ionic compound consists of a positively charged ion and a negatively charged anion. For example, NaCl. Na (sodium) is a cation (another word for positively charged ion) and Cl (chloride) is a anion (another way for negatively charged ion.)
Molecular compounds consists of only negatively charged ions. For example Br2I is a compound of 2 elements that are negatively charged.
Unlike ionic compounds, molecular compounds consists of two or more negatively charged elements.
It must be made of matter because anything and everything is made up of atoms. The other three options are made of atoms but they are also matter.
The correct answer is A. Alkali metals.
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The independent variable is a variable that is being manipulated or controlled. This is to see how it affects, changes and yields the outcome of the particular stimuli.
The dry ice experiment has an IV of temperature and a DV of melting time.