What are mixtures that have evenly mixed groups of particles that do not settle out called? colloidsheterogeneous mixtureshomogenous mixtures?

oxygen is the first element in group 16 (via) of the periodic table. the periodic table is a chart that shows how chemical elements are related to each other. the elements in group 16 are said to belong to the chalcogen family. other elements in this group include  sulfur, selenium, tellurium,  and  polonium.  the name chalcogen comes from the greek word  chalkos,  meaning "ore." the first two members of the family, oxygen and sulfur, are found in most ores.

oxygen is by far the most abundant element in the earth's crust. nearly half of all the atoms in the earth are oxygen atoms. oxygen also makes up about one-fifth of the earth's atmosphere. nearly 90 percent of the weight of the oceans is due to oxygen. in addition, oxygen is thought to be the third most abundant element in the universe and in the solar system.

bradycardia ( blood presssure below 120/80mmhg )

it is contraindicated to give nitroglycerin to patients with blood pressure that is lower than normal range because the drug can cause blood pressure to drop further. it can lead to paradoxical bradycardia and less commonly, threatening hypotension.