This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

[Q]: In an effort to demonstrate peaceful intentions toward Germany, on 13 April 1941, the Soviets signed a neutrality pact with Axis power Japan. While Stalin had little faith in Japan's commitment to neutrality, he felt that the pact was important for its political symbolism, to reinforce a public affection for Germany. Stalin felt that there was a growing split in German circles about whether Germany should initiate a war with the Soviet Union. Stalin did not know that Hitler had been secretly discussing an invasion of the Soviet Union since summer 1940, and that Hitler had ordered his military in late 1940 to prepare for war in the east regardless of the parties' talks of a potential Soviet entry as a fourth Axis Power.
[A]: Who was planning an invasion of the Soviet Union?

[Q]: There are several reasons an otherwise valid and agreed upon treaty may be rejected as a binding international agreement, most of which involve problems created at the formation of the treaty.[citation needed] For example, the serial Japan-Korea treaties of 1905, 1907 and 1910 were protested; and they were confirmed as "already null and void" in the 1965 Treaty on Basic Relations between Japan and the Republic of Korea.
[A]: When are most of the problems created that might result in an otherwise valid treaty being rejected as a binding international agreement?

[Q]: Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abu Rayhan al-Biruni in the early 11th century. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235. Abu Rayhan al-Biruni invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels, circa 1000 AD.
[A]:
Who invented the planisphere?