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xenon

(Encyclopedia)xenon zēˈnŏn [key] [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.293; m.p. −111.9℃; b.p. −107.1℃; density 5.86 grams per liter at STP; valence usually 0. Xeno...

Rowhani, Hassan

(Encyclopedia)Rowhani, Hassan häsänˈ rōhänēˈ [key], 1948–, Iranian cleric and political leader, b. Sorkheh, ...

helium

(Encyclopedia)helium hēˈlēəm [key], gaseous chemical element; symbol He; at. no. 2; at. wt. 4.0026; m.p. below −272℃ at 26 atmospheres pressure; b.p. −268.934℃ at 1 atmosphere pressure; density 0.1785 g...

lanthanum

(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...

Vendée

(Encyclopedia)Vendée väNdāˈ [key], department (1990 pop. 509,356), W France, on the Bay of Biscay, in Poitou. The offshore islands of Noirmoutier and Yeu are included in the department. Largely an agricultural ...

promethium

(Encyclopedia)promethium prōmēˈthēəm [key], artificially produced radioactive chemical element; symbol Pm; at. no. 61; mass no. of most stable isotope 145; m.p. 1,042℃; b.p. 3,000℃ (estimated); sp. gr. unk...

hydrogen bomb

(Encyclopedia)hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that togethe...

Niger, country, Africa

(Encyclopedia)CE5 Niger nīˈjər, nēzhârˈ [key], officially Republic of Niger, republic (2015 est. pop. 18,045,729), 489,189 sq mi (1,267,000 sq km), W Africa. It borders on Burkina Faso and Mali in the west...

Mogadishu

(Encyclopedia)Mogadishu or Mogadisho both: mŏgədĭshˈo͞o [key], Ital. Mogadiscio, city (1990 est. pop. 1,200,000), capital of Somalia, on the Indian Ocean. It is the country's largest city, a port, and a commer...

krypton

(Encyclopedia)krypton krĭpˈtŏn [key] [Gr.,=hidden], gaseous chemical element; symbol Kr; at. no. 36; at. wt. 83.798; m.p. −156.6℃; b.p. −152.3℃; density 3.73 grams per liter at STP; valence usually 0. Kr...