Article: In the 1930s, record companies began issuing collections of 78 rpm records by one performer or of one type of music in specially assembled albums, typically with artwork on the front cover and liner notes on the back or inside cover. Most albums included three or four records, with two sides each, making six or eight tunes per album. When the 12-inch vinyl LP era began in 1949, the single record often had the same or similar number of tunes as a typical album of 78s, and was still often referred to as an "album".

Question: How may records were commonly found in an album?
Ans: three or four


Article: The territory of modern-day Mexico was home to numerous indigenous civilizations prior to the arrival of the Spanish conquistadores: The Olmecs, who flourished from between 1200 BCE to about 400 BCE in the coastal regions of the Gulf of Mexico; the Zapotecs and the Mixtecs, who held sway in the mountains of Oaxaca and the Isthmus of Tehuantepec; the Maya in the Yucatan (and into neighbouring areas of contemporary Central America); the Purépecha in present-day Michoacán and surrounding areas, and the Aztecs/Mexica, who, from their central capital at Tenochtitlan, dominated much of the centre and south of the country (and the non-Aztec inhabitants of those areas) when Hernán Cortés first landed at Veracruz.

Question: What was Mexico home to prior to the arrival of the Spaniards?
Ans: indigenous civilizations


Article: At the 2009 American Community Survey, Black Americans made the second largest group in the Bronx after Hispanics and Latinos. Blacks of both Hispanic and non-Hispanic origin represented over one-third (35.4%) of the Bronx's population. Blacks of non-Hispanic origin made up 30.8% of the population. Over 495,200 blacks resided in the borough, of which 430,600 were non-Hispanic blacks. Over 61,000 people identified themselves as "Sub-Saharan African" in the survey, making up 4.4% of the population.

Question: How many Bronx residents called themselves "Sub-Saharan African" in 2009?
Ans: Over 61,000


Article: These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves.

Question: How can anaerobes adjust to the surrounding environment?
Ans:
can switch between fermentation and different terminal electron acceptors