Problem: Neptune:

Neptune's more varied weather when compared to Uranus is due in part to its higher internal heating. Although Neptune lies over 50% further from the Sun than Uranus, and receives only 40% its amount of sunlight, the two planets' surface temperatures are roughly equal. The upper regions of Neptune's troposphere reach a low temperature of 51.8 K (221.3 C). At a depth where the atmospheric pressure equals 1 bar (100 kPa), the temperature is 72.00 K (201.15 C). Deeper inside the layers of gas, the temperature rises steadily. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun; whereas Neptune radiates about 2.61 times as much energy as it receives from the Sun. Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Depending on the thermal properties of its interior, the heat left over from Neptune's formation may be sufficient to explain its current heat flow, though it is more difficult to simultaneously explain Uranus's lack of internal heat while preserving the apparent similarity between the two planets.

The current cold flow on Neptune might be explained by what?
---
A: unanswerable

Problem: Russian language:

In Kazakhstan Russian is not a state language, but according to article 7 of the Constitution of Kazakhstan its usage enjoys equal status to that of the Kazakh language in state and local administration. According to estimates from Demoskop Weekly, in 2004 there were 4,200,000 native speakers of Russian in the country, and 10 million active speakers. 63% of the population was fluent in Russian in 2006, and 46% used it as the main language with family, friends or at work. According to a 2001 estimate from the World Factbook, 95% of the population can speak Russian. Large Russian-speaking communities still exist in northern Kazakhstan, and ethnic Russians comprise 25.6% of Kazakhstan's population. The 2009 census reported that 10,309,500 people, or 84.8% of the population aged 15 and above, could read and write well in Russian, as well as understand the spoken language.

How much of the population aged 15 and above used the World Factbook in school in 2009?
---
A: unanswerable

Problem: Electric motor:

Since the armature windings of a direct-current or universal motor are moving through a magnetic field, they have a voltage induced in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (emf)". The voltage is proportional to the running speed of the motor. The back emf of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back emf results, and more current is drawn from the supply. This increased current provides the additional torque to balance the new load.

Voltage at the brushes is equal to what?
---
A: back emf of the motor, plus the voltage drop across the winding internal resistance

Problem: Transistor:

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

Why does a transistor increase a signal?
---
A:
the controlled (output) power can be higher than the controlling (input) power