Question: A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.
Is there an answer to this question: Why is the use of solar balloons typically limited to the toy market?

Answer: the surface-area to payload-weight ratio is relatively high


Question: Pascal Lissouba, who became Congo's first elected president (1992–1997) during the period of multi-party democracy, attempted to implement economic reforms with IMF backing to liberalise the economy. In June 1996 the IMF approved a three-year SDR69.5m (US$100m) enhanced structural adjustment facility (ESAF) and was on the verge of announcing a renewed annual agreement when civil war broke out in Congo in mid-1997.
Is there an answer to this question: Who was president during the period of single party democracy?

Answer: unanswerable


Question: Queen drew artistic influence from British rock acts of the 1960s and early 1970s, such as the Beatles, the Kinks, Cream, Led Zeppelin, Pink Floyd, the Who, Black Sabbath, Slade, Deep Purple, David Bowie, Genesis and Yes, in addition to American guitarist Jimi Hendrix, with Mercury also inspired by the gospel singer Aretha Franklin. May referred to the Beatles as being "our bible in the way they used the studio and they painted pictures and this wonderful instinctive use of harmonies." At their outset in the early 1970s, Queen's music has been characterised as "Led Zeppelin meets Yes" due to its combination of "acoustic/electric guitar extremes and fantasy-inspired multi-part song epics".
Is there an answer to this question: What nationality were the rock groups that influenced Queen?

Answer: British


Question: Hops contain several characteristics that brewers desire in beer. Hops contribute a bitterness that balances the sweetness of the malt; the bitterness of beers is measured on the International Bitterness Units scale. Hops contribute floral, citrus, and herbal aromas and flavours to beer. Hops have an antibiotic effect that favours the activity of brewer's yeast over less desirable microorganisms and aids in "head retention", the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative.
Is there an answer to this question: What is retention head?

Answer:
unanswerable