Answer: (3) silicon
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Silicon (Si)
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: ethane 
, propanone 
and water 
Answer:
Arrhenius Base
Explanation:
"NaOH is an Arrhenius base because it dissociates in water to give the hydroxide (OH-) and sodium (Na+) ions. An Arrhenius acid is therefore any substance that ionizes when it dissolves in water to give the H+, or hydrogen, ion. ... Acids provide the H+ ion; bases provide the OH- ion; and these ions combine to form water."
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Amplifiers and watts and decibels <span />
Answer:
Changing two or more variables makes it difficult to find a cause and effect relationship.
