Problem: Paper:

Paper made from mechanical pulp contains significant amounts of lignin, a major component in wood. In the presence of light and oxygen, lignin reacts to give yellow materials, which is why newsprint and other mechanical paper yellows with age. Paper made from bleached kraft or sulfite pulps does not contain significant amounts of lignin and is therefore better suited for books, documents and other applications where whiteness of the paper is essential.

When lacking light and oxygen, what type of materials does lignin react to give?
---
A: unanswerable

Problem: In 1744, Burke started at Trinity College Dublin, a Protestant establishment, which up until 1793, did not permit Catholics to take degrees. In 1747, he set up a debating society, "Edmund Burke's Club", which, in 1770, merged with TCD's Historical Club to form the College Historical Society; it is the oldest undergraduate society in the world. The minutes of the meetings of Burke's Club remain in the collection of the Historical Society. Burke graduated from Trinity in 1748. Burke's father wanted him to read Law, and with this in mind he went to London in 1750, where he entered the Middle Temple, before soon giving up legal study to travel in Continental Europe. After eschewing the Law, he pursued a livelihood through writing.
When did Burke begin attending Trinity College Dublin?
---
Answer: 1744

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The essence of air defence is to detect hostile aircraft and destroy them. The critical issue is to hit a target moving in three-dimensional space; an attack must not only match these three coordinates, but must do so at the time the target is at that position. This means that projectiles either have to be guided to hit the target, or aimed at the predicted position of the target at the time the projectile reaches it, taking into account speed and direction of both the target and the projectile.
What two things must be considered in regards to the projectile and target?
A: speed and direction

Context and question: During the American occupation of the state, the number of Indian attacks was drastically reduced, but in 1848 the attacks resumed to such a degree that the Mexican officials had no choice but to resume military projects to protect Mexican settlements in the state. Through the next three decades the state faced constant attacks from indigenous on Mexican settlements. After the occupation the people of the state were worried about the potential attack from the hostile indigenous tribes north of the Rio Grande; as a result a decree on July 19, 1848, the state established 18 military colonies along the Rio Grande. The new military colonies were to replace the presidios as population centers to prevent future invasions by indigenous tribes; these policies remained prominent in the state until 1883. Eventually the state replaced the old state security with a state policy to form militias organized with every Mexican in the state capable to serve between the ages of 18 and 55 to fulfill the mandate of having six men defending for every 1000 residents.
How many military colonies were established by the state?
Answer: 18

Question: Historians trace the earliest Baptist church back to 1609 in Amsterdam, with John Smyth as its pastor. Three years earlier, while a Fellow of Christ's College, Cambridge, he had broken his ties with the Church of England. Reared in the Church of England, he became "Puritan, English Separatist, and then a Baptist Separatist," and ended his days working with the Mennonites. He began meeting in England with 6070 English Separatists, in the face of "great danger." The persecution of religious nonconformists in England led Smyth to go into exile in Amsterdam with fellow Separatists from the congregation he had gathered in Lincolnshire, separate from the established church (Anglican). Smyth and his lay supporter, Thomas Helwys, together with those they led, broke with the other English exiles because Smyth and Helwys were convinced they should be baptized as believers. In 1609 Smyth first baptized himself and then baptized the others.
Is there an answer to this question: In what year did Smyth baptize himself for the second time?

Answer: unanswerable

Problem: Railway electrification system:

Disadvantages of electric traction include high capital costs that may be uneconomic on lightly trafficked routes; a relative lack of flexibility since electric trains need electrified tracks or onboard supercapacitors and charging infrastructure at stations; and a vulnerability to power interruptions. Different regions may use different supply voltages and frequencies, complicating through service. The limited clearances available under catenaries may preclude efficient double-stack container service. The lethal voltages on contact wires and third rails are a safety hazard to track workers, passengers and trespassers. Overhead wires are safer than third rails, but they are often considered unsightly.

Lethal voltages on contact wires and third rails are non a safety hazard for whom?
---
A:
unanswerable