Cale on the How do scientists use parallax to measure the distance to nearby stars?
A Parallax increases the focal length of the lens in a telescope.
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B.
Parallax helps classify stars according to brightness and temperature.
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C. Parallax shows the apparent movement of a star seen from different positions.
D. Parallax helps identify the chemical composition of stars.
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16

explanation:

the marks go by 4s

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.