Which phrases describe space observatories?

1.are telescopes that can images of invisible energy

2.are located on Earth's surface away from areas of light pollution

3.observed electromagnetic radiation that is blocked by our atmosphere

4.observe only electromagnetic radiation that makes it through Earth's atmosphere

5.are large observation decks in space where humans can conduct experiments

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

14 days is the half-life of phosphorus-32

56 moles of   lieter in chemistry