Answer:
1) Constructive Interference
2) Hits a surface and bounces back
3) Antinodes
I am thinking it is c) A microscope is used to magnify a group of cells on a slide.
Answer:
Groups like the Halogens, which include Chlorine and Flourine, share similar properties both behaviorally and structurally. The Periodic Table is essentially a bunch of patterns and trends and the groups (like the one with Sodium and Potassium) were grouped together because of these similarities.
Explanation:
https://en.wikipedia.org/wiki/Alkali_metal
