PLEASE HELP match the following people with their contributions to chemistry.

1. Bohr
2. Dalton
3. Mendeleev

A. Developed an atomic theory that describes the characteristics of atoms.
B. Developed the periodic table of elements format we still use today.
C. Established that electrons exist in specific energy levels using the element hydrogen.

Litmus paper is made from water-soluble dyes which are extracted from lichens. this paper is used as an acid-base indicator. which of these common household substances would turn blue litmus paper red? a) bleach b) lye c) soap d) vinegar

Which statement best describes the relationship between period and frequency of light waves? a) in wave b the period increases and the frequency decreases from wave a. b) in wave a the period increases and the frequency decreases from wave b. c) in wave b the period is shorter and the frequency is greater than in wave a. d) in wave a the period is shorter and the frequency is greater than in wave b.

Identify the electromagnets with poles that are reversed from the electromagnet shown above