Salts of many oxidation states of uranium are water-soluble and may be studied in aqueous solutions. The most common ionic forms are U3+ (brown-red), U4+ (green), UO+
2 (unstable), and UO2+
2 (yellow), for U(III), U(IV), U(V), and U(VI), respectively. A few solid and semi-metallic compounds such as UO and US exist for the formal oxidation state uranium(II), but no simple ions are known to exist in solution for that state. Ions of U3+ liberate hydrogen from water and are therefore considered to be highly unstable. The UO2+
2 ion represents the uranium(VI) state and is known to form compounds such as uranyl carbonate, uranyl chloride and uranyl sulfate. UO2+
2 also forms complexes with various organic chelating agents, the most commonly encountered of which is uranyl acetate.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What is the color of U4+?
Ah, so.. green

Friederike Muller, a pupil of Chopin, wrote: "[His] playing was always noble and beautiful; his tones sang, whether in full forte or softest piano. He took infinite pains to teach his pupils this legato, cantabile style of playing. His most severe criticism was 'Heor shedoes not know how to join two notes together.' He also demanded the strictest adherence to rhythm. He hated all lingering and dragging, misplaced rubatos, as well as exaggerated ritardandos ... and it is precisely in this respect that people make such terrible errors in playing his works."
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): According to who did Chopin demand strictly sticking with rhythm?
Ah, so.. Friederike Muller

This season saw the first Idol Gives Back telethon-inspired event, which raised more than $76 million in corporate and viewer donations. No contestant was eliminated that week, but two (Phil Stacey and Chris Richardson) were eliminated the next. Melinda Doolittle was eliminated in the final three.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): How much money did the Idol Gives Back event raise in 2007?
Ah, so..
$76 million