Problem: Incandescent light bulb:

In flood lamps used for photographic lighting, the tradeoff is made in the other direction. Compared to general-service bulbs, for the same power, these bulbs produce far more light, and (more importantly) light at a higher color temperature, at the expense of greatly reduced life (which may be as short as two hours for a type P1 lamp). The upper temperature limit for the filament is the melting point of the metal. Tungsten is the metal with the highest melting point, 3,695 K (6,191 F). A 50-hour-life projection bulb, for instance, is designed to operate only 50 C (122 F) below that melting point. Such a lamp may achieve up to 22 lumens per watt, compared with 17.5 for a 750-hour general service lamp.

What metal is used with the lowest melting point?
---
A: unanswerable

Problem: Slavs:

Proto-Slavic, sometimes referred to as Common Slavic or Late Proto-Slavic, is defined as the last stage of the language preceding the geographical split of the historical Slavic languages. That language was uniform, and on the basis of borrowings from foreign languages and Slavic borrowings into other languages, cannot be said to have any recognizable dialects, suggesting a comparatively compact homeland. Slavic linguistic unity was to some extent visible as late as Old Church Slavonic manuscripts which, though based on local Slavic speech of Thessaloniki, could still serve the purpose of the first common Slavic literary language.

What is Thessaloniki the first example of?
---
A: unanswerable

Problem: Queen (band):

After the band's six-night stand at New York's Uris Theatre in May 1974, Brian May collapsed and was diagnosed as having hepatitis. While recuperating, May was initially absent when the band started work on their third album, but he returned midway through the recording process. Released in 1974, Sheer Heart Attack reached number two in the United Kingdom, sold well throughout Europe, and went gold in the United States. It gave the band their first real experience of international success, and was a hit on both sides of the Atlantic. The album experimented with a variety of musical genres, including British music hall, heavy metal, ballads, ragtime, and Caribbean. At this point, Queen started to move away from the progressive tendencies of their first two releases into a more radio-friendly, song-orientated style. Sheer Heart Attack introduced new sound and melody patterns that would be refined on their next album, A Night at the Opera.

Queen's Sheer Heart Attack reached what number on the United Kingdom charts?
---
A: two

Problem: Palermo:

The port of Palermo, founded by the Phoenicians over 2,700 years ago, is, together with the port of Messina, the main port of Sicily. From here ferries link Palermo to Cagliari, Genoa, Livorno, Naples, Tunis and other cities and carry a total of almost 2 million passengers annually. It is also an important port for cruise ships. Traffic includes also almost 5 million tonnes of cargo and 80.000 TEU yearly. The port also has links to minor sicilian islands such as Ustica and the Aeolian Islands (via Cefalu in summer). Inside the Port of Palermo there is a section known as "tourist marina" for sailing yachts and catamarans.

What cities do the ferries of Palermo travel to?
---
A:
Cagliari, Genoa, Livorno, Naples, Tunis