D. So far, various exoplanet surveys have discovered and confirmed 4,000 exoplanets, with thousands more awaiting confirmation.
C. Mini-Neptunes. These exoplanets are between the masses of Earth and Neptune, and they generally have a rocky core and a surrounding envelope of helium and hydrogen.
A. True. Exoplanet K2-141 b, orbiting a star 200,000 lightyears away, gets so hot that rock vaporizes, condenses, and rains.
A. Also true! Exoplanet WASP-76b’s surface temperatures reach up to 13,000 degrees Fahrenheit, meaning iron could be vaporized, condensed, and then rained out.