Problem: In 1847, Hungarian physician Ignac Fulop Semmelweis dramatically reduced the occurrency of puerperal fever by simply requiring physicians to wash their hands before attending to women in childbirth. This discovery predated the germ theory of disease. However, Semmelweis' findings were not appreciated by his contemporaries and came into use only with discoveries by British surgeon Joseph Lister, who in 1865 proved the principles of antisepsis. Lister's work was based on the important findings by French biologist Louis Pasteur. Pasteur was able to link microorganisms with disease, revolutionizing medicine. He also devised one of the most important methods in preventive medicine, when in 1880 he produced a vaccine against rabies. Pasteur invented the process of pasteurization, to help prevent the spread of disease through milk and other foods.
What came after the realization that physicians should was their hands before childbirth?
The answer is the following: the germ theory of disease

Problem: In 2010 and 2011, state and federal funds were awarded to Connecticut (and Massachusetts) to construct the Hartford Line, with a southern terminus at New Haven's Union Station and a northern terminus at Springfield's Union Station. According to the White House, "This corridor [currently] has one train per day connecting communities in Connecticut and Massachusetts to the Northeast Corridor and Vermont. The vision for this corridor is to restore the alignment to its original route via the Knowledge Corridor in western Massachusetts, improving trip time and increasing the population base that can be served." Set for construction in 2013, the "Knowledge Corridor high speed intercity passenger rail" project will cost approximately $1 billion, and the ultimate northern terminus for the project is reported to be Montreal in Canada. Train speeds between will reportedly exceed 110 miles per hour (180 km/h) and increase both cities' rail traffic exponentially.
Where is the starting point of the terminus line in New Haven?
The answer is the following: New Haven's Union Station

Problem: French-speaking naturalists in several countries showed appreciation of the much modified French translation by Clemence Royer, but Darwin's ideas had little impact in France, where any scientists supporting evolutionary ideas opted for a form of Lamarckism. The intelligentsia in Russia had accepted the general phenomenon of evolution for several years before Darwin had published his theory, and scientists were quick to take it into account, although the Malthusian aspects were felt to be relatively unimportant. The political economy of struggle was criticised as a British stereotype by Karl Marx and by Leo Tolstoy, who had the character Levin in his novel Anna Karenina voice sharp criticism of the morality of Darwin's views.
Which author voiced his displeasure of the morality of Darwin's views in a novel?
The answer is the following: Leo Tolstoy

Problem: In October 1810, six months after Fryderyk's birth, the family moved to Warsaw, where his father acquired a post teaching French at the Warsaw Lyceum, then housed in the Saxon Palace. Fryderyk lived with his family in the Palace grounds. The father played the flute and violin; the mother played the piano and gave lessons to boys in the boarding house that the Chopins kept. Chopin was of slight build, and even in early childhood was prone to illnesses.
What instrument did Chopin's mother teach?
The answer is the following:
piano