On the periodic table how many periods are there and how many columns are there

Match each object to its description: a. coma of a comet b. comet tail c. oort cloud haze surrounding a nucleus created by solar wind. hypothetical sphere around the solar system

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

The organism shown is a free-living one that is anchored to the bottom of ponds and streams during one stage of its life cycle what is the common name for the group to which this organism belong