Question: Subtractive methods remove copper from an entirely copper-coated board to leave only the desired copper pattern. In additive methods the pattern is electroplated onto a bare substrate using a complex process. The advantage of the additive method is that less material is needed and less waste is produced. In the full additive process the bare laminate is covered with a photosensitive film which is imaged (exposed to light through a mask and then developed which removes the unexposed film). The exposed areas are sensitized in a chemical bath, usually containing palladium and similar to that used for through hole plating which makes the exposed area capable of bonding metal ions. The laminate is then plated with copper in the sensitized areas. When the mask is stripped, the PCB is finished.
Is there an answer to this question: What object is used to expose selected parts of the photosensitive film to light?

Answer: mask

Question: Karl Popper's rejection of Marxism during his teenage years left a profound mark on his thought. He had at one point joined a socialist association, and for a few months in 1919 considered himself a communist. During this time he became familiar with the Marxist view of economics, class-war, and history. Although he quickly became disillusioned with the views expounded by Marxism, his flirtation with the ideology led him to distance himself from those who believed that spilling blood for the sake of a revolution was necessary. He came to realise that when it came to sacrificing human lives, one was to think and act with extreme prudence.
Is there an answer to this question: What ideology did Popper never become disillusioned with?

Answer: unanswerable

Question: The Royal College of Chemistry was established by private subscription in 1845 as there was a growing awareness that practical aspects of the experimental sciences were not well taught and that in the United Kingdom the teaching of chemistry in particular had fallen behind that in Germany. As a result of a movement earlier in the decade, many politicians donated funds to establish the college, including Benjamin Disraeli, William Gladstone and Robert Peel. It was also supported by Prince Albert, who persuaded August Wilhelm von Hofmann to be the first professor.
Is there an answer to this question: Who was the first professor of the college?

Answer: August Wilhelm von Hofmann

Question: The primary responsibility for a boy's studies lies with his House Master, but he is assisted by an additional director of studies, known as a tutor. Classes, colloquially known as "divs" (divisions), are organised on a School basis; the classrooms are separate from the houses. New school buildings have appeared for teaching purposes every decade or so since New Schools, designed by Henry Woodyer and built 1861-3. Despite the introduction of modern technology, the external appearance and locations of many of the classrooms have remained unchanged for a long time.
Is there an answer to this question: What is New Schools colloquially known as?

Answer:
unanswerable