Assertion and reason questions?

Graphite, named by Abraham Gottlob Werner in 1789, from the Greek γράφειν (graphein, "to draw/write", for its use in pencils) is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under standard conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Graphite conducts electricity, due to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted along the plane of the layers. In diamond, all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane. Graphite powder is used as a dry lubricant. Although it might be thought that this industrially important property is due entirely to the loose interlamellar coupling between sheets in the structure, in fact in a vacuum environment (such as in technologies for use in space), graphite was found to be a very poor lubricant. This fact led to the discovery that graphite's lubricity is due to adsorbed air and water between the layers, unlike other layered dry lubricants such as molybdenum disulfide. Recent studies suggest that an effect called superlubricity can also account for this effect. When a large number of crystallographic defects(physical) bind these planes together, graphite loses its lubrication properties and becomes what is known as pyrolytic carbon, a useful material in blood-contacting implants such as prosthetic heart valves. Graphite is the most stable allotrope of carbon. Contrary to popular belief, high-purity graphite does not readily burn, even at elevated temperatures.[3] For this reason, it is used in nuclear reactors and for high-temperature crucibles for melting metals. Natural and crystalline graphites are not often used in pure form as structural materials due to their shear-planes, brittleness and inconsistent mechanical properties. In its pure glassy (isotropic) synthetic forms, pyrolytic graphite and carbon fiber graphite are extremely strong, heat-resistant (to 3000 °C) materials, used in reentry shields for missile nosecones, solid rocket engines, high temperature reactors, brake shoes and electric motor brushes. Intumescent or expandable graphites are used in fire seals, fitted around the perimeter of a fire door. During a fire the graphite intumesces (expands and chars) to resist fire penetration and prevent the spread of fumes.

Example 2: Assertion: The Mountains on Moon are way taller than Mount Everest. Reason: The force of gravity is stronger on Earth than on the moon. (A) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion. (B) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion. (C) Our Assertion is true but the Reason is false. (D) The statement of the Assertion is false but the Reason is true. (E) Both the statements are false. Answer: The two statements don’t seem to have the same topic but that doesn’t matter. The reason that the height of Everest is not greater than the mountains on the surface of the moon is gravity. The stronger force of gravity on the surface of earth makes sure that the mountains are shorter. Thus the reason and assertion are not only true but the reason is the correct explanation of the assertion. Therefore the answer is ). Example 3: Assertion: Humans have evolved from an ape-like species of primates. Reason: There are many fossils that support the theory of evolution in case of humans. Answer: You might be tempted to select A) here but wait, there is caution here. The answer is not A). Of course, humans are evolved from apes and there are fossils that support the theory of evolution. But the reason has to explain why humans have evolved from apes. A simple trick to see if reason explains the assertion is to change the assertion into a question. For example, here the assertion becomes, “why have humans evolved from apes?” or “How have humans evolved from apes”. The reason doesn’t answer that. So both the statements are correct but the reason is the explanation of the assertion. Therefore the correct option here is B). Practice Questions Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following: (A) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion. (B) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion. (C) Our Assertion is true but the Reason is false. (D) The statement of the Assertion is false but the Reason is true. (E) Both the statements are false. Q 1: Assertion: Dogs are easily one of the most social creatures on earth. Reason: Dogs have been artificially bred from wolves over several generations. Ans: A) Q 2: Assertion: Music is soothing to everybody. Reason: The rhythmic sounds stimulate the brain and produce a soothing effect. Ans: D)