Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Fused quartz is a glass made from chemically-pure SiO2 (silica). It has excellent thermal shock characteristics, being able to survive immersion in water while red hot. However, its high melting-temperature (1723 °C) and viscosity make it difficult to work with. Normally, other substances are added to simplify processing. One is sodium carbonate (Na2CO3, "soda"), which lowers the glass transition temperature. The soda makes the glass water-soluble, which is usually undesirable, so lime (calcium oxide [CaO], generally obtained from limestone), some magnesium oxide (MgO) and aluminium oxide (Al2O3) are added to provide for a better chemical durability. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass. Soda-lime glasses account for about 90% of manufactured glass.
What percentage of soda-lime glass is obtained from limestone?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Iran consists of the Iranian Plateau with the exception of the coasts of the Caspian Sea and Khuzestan Province. It is one of the world's most mountainous countries, its landscape dominated by rugged mountain ranges that separate various basins or plateaux from one another. The populous western part is the most mountainous, with ranges such as the Caucasus, Zagros and Alborz Mountains; the last contains Iran's highest point, Mount Damavand at 5,610 m (18,406 ft), which is also the highest mountain on the Eurasian landmass west of the Hindu Kush.
What is Iran's highest mountain?
A: Mount Damavand

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Southeast Raleigh is bounded by downtown on the west, Garner on the southwest, and rural Wake County to the southeast. The area includes areas along Rock Quarry Road, Poole Road, and New Bern Avenue. Primary neighborhoods include Chastain, Chavis Heights, Raleigh Country Club, Southgate, Kingwood Forest, Rochester Heights, Emerald Village and Biltmore Hills. Time Warner Cable Music Pavilion (formerly Alltel Pavilion and Walnut Creek Amphitheatre) is one of the region's major outdoor concert venues and is located on Rock Quarry Road. Shaw University is located in this part of the city.
What areas are in Southeast Raleigh?
A: Rock Quarry Road, Poole Road, and New Bern Avenue

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Rutherford centralized organizational control of the Watch Tower Society. In 1919, he instituted the appointment of a director in each congregation, and a year later all members were instructed to report their weekly preaching activity to the Brooklyn headquarters. At an international convention held at Cedar Point, Ohio, in September 1922, a new emphasis was made on house-to-house preaching. Significant changes in doctrine and administration were regularly introduced during Rutherford's twenty-five years as president, including the 1920 announcement that the Jewish patriarchs (such as Abraham and Isaac) would be resurrected in 1925, marking the beginning of Christ's thousand-year Kingdom. Disappointed by the changes, tens of thousands of defections occurred during the first half of Rutherford's tenure, leading to the formation of several Bible Student organizations independent of the Watch Tower Society, most of which still exist. By mid-1919, as many as one in seven of Russell-era Bible Students had ceased their association with the Society, and as many as two-thirds by the end of the 1920s.
What was a new emphasis made on at the international convention?
A:
house-to-house preaching