What did Thomson contribute to atomic theory? A. The discovery that positive charge is concentrated in a core, or nucleus
B. The discovery that negative charge is concentrated in a core, or nucleus
C. The discovery of negatively charged particles, now called electrons
D. The idea that electrons have quantized amounts of energy

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium