QUES: When a molten metal is mixed with another substance, there are two mechanisms that can cause an alloy to form, called atom exchange and the interstitial mechanism. The relative size of each element in the mix plays a primary role in determining which mechanism will occur. When the atoms are relatively similar in size, the atom exchange method usually happens, where some of the atoms composing the metallic crystals are substituted with atoms of the other constituent. This is called a substitutional alloy. Examples of substitutional alloys include bronze and brass, in which some of the copper atoms are substituted with either tin or zinc atoms. With the interstitial mechanism, one atom is usually much smaller than the other, so cannot successfully replace an atom in the crystals of the base metal. The smaller atoms become trapped in the spaces between the atoms in the crystal matrix, called the interstices. This is referred to as an interstitial alloy. Steel is an example of an interstitial alloy, because the very small carbon atoms fit into interstices of the iron matrix. Stainless steel is an example of a combination of interstitial and substitutional alloys, because the carbon atoms fit into the interstices, but some of the iron atoms are replaced with nickel and chromium atoms.

What is formed when molten metal is separated from other substances?
What is the answer?
ANS: unanswerable
QUES: Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster and smoother service, and the fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades.

What can be seen in the newly electrified lines?
What is the answer?
ANS: "sparks effect"
QUES: Since the university's establishment in the city in 1837, the histories of the University of Michigan and Ann Arbor have been closely linked. The town became a regional transportation hub in 1839 with the arrival of the Michigan Central Railroad, and a north—south railway connecting Ann Arbor to Toledo and other markets to the south was established in 1878. Throughout the 1840s and the 1850s settlers continued to come to Ann Arbor. While the earlier settlers were primarily of British ancestry, the newer settlers also consisted of Germans, Irish, and African-Americans. In 1851, Ann Arbor was chartered as a city, though the city showed a drop in population during the Depression of 1873. It was not until the early 1880s that Ann Arbor again saw robust growth, with new immigrants coming from Greece, Italy, Russia, and Poland. Ann Arbor saw increased growth in manufacturing, particularly in milling. Ann Arbor's Jewish community also grew after the turn of the 20th century, and its first and oldest synagogue, Beth Israel Congregation, was established in 1916.

Which town became the regional transport hub in 1878?
What is the answer?
ANS:
Ann Arbor