QUES: Although an alloy is technically an impure metal, when referring to alloys, the term "impurities" usually denotes those elements which are not desired. These impurities are often found in the base metals or the solutes, but they may also be introduced during the alloying process. For instance, sulfur is a common impurity in steel. Sulfur combines readily with iron to form iron sulfide, which is very brittle, creating weak spots in the steel. Lithium, sodium and calcium are common impurities in aluminium alloys, which can have adverse effects on the structural integrity of castings. Conversely, otherwise pure-metals that simply contain unwanted impurities are often called "impure metals" and are not usually referred to as alloys. Oxygen, present in the air, readily combines with most metals to form metal oxides; especially at higher temperatures encountered during alloying. Great care is often taken during the alloying process to remove excess impurities, using fluxes, chemical additives, or other methods of extractive metallurgy.

What is a rare impurity in steel?
What is the answer?
ANS: unanswerable
QUES: Catalan has inherited the typical vowel system of Vulgar Latin, with seven stressed phonemes: /a ɛ e i ɔ o u/, a common feature in Western Romance, except Spanish. Balearic has also instances of stressed /ə/. Dialects differ in the different degrees of vowel reduction, and the incidence of the pair /ɛ e/.

What is the vowel system of Catalan?
What is the answer?
ANS: Vulgar Latin
QUES: The simplest known circadian clock is that of the prokaryotic cyanobacteria. Recent research has demonstrated that the circadian clock of Synechococcus elongatus can be reconstituted in vitro with just the three proteins (KaiA, KaiB, KaiC) of their central oscillator. This clock has been shown to sustain a 22-hour rhythm over several days upon the addition of ATP. Previous explanations of the prokaryotic circadian timekeeper were dependent upon a DNA transcription/translation feedback mechanism.[citation needed]

What was the minimum amount of time the clock could be sustained in vitro?
What is the answer?
ANS:
unanswerable