The most common questions with answers on chemistry are listed below:
Q 1. What is a teleprinter?
Ans. In this the operator at the sending station presses the key corresponding to a particular letter, and the same letter is recorded automatically at the receiving station; the signal being carried through the medium of wireless waves. It literally means printing at a distance.
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Q 2. What is hydro-electric power?
Ans. To produce electricity, the armature of a dynamo must be continuously rotated in a magnetic field. This is done by the use of running or falling water. Electric power thus produced is called hydro-electric power.
Q 3. What is nuclear fission?
Ans. It is a nuclear reaction in which the nucleus of an atom (e.g., uranium 235, Plutonium) captures a neutron, and the unstable nucleus so produced breaks into two nearly equal fragments.
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Also released in the process are several neutrons and a lot of energy. In case one of the neutrons released is captured by other uranium atoms, it too splits. This process if carried on results in self-sustaining nuclear fission and is called a chain reaction.
Q 4. What is nuclear fusion?
Ans. The ability of two light nuclei to combine and form a heavier nucleus is called fusion. The reaction occurs with a release of energy. A typical nuclear fusion reaction involves the interaction of Deuterium nuclei to produce Helium nuclei.
To obtain a net gain in energy from this process, temperature must be raised to and held at millions of degrees Celsius which brings in its wake problems of metallurgy. Because of such technical problems, nuclear fusion is not yet commercially viable, even though it provides a clean source of nuclear energy, without any radioacative byproducts of the kind produced in fission.
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Q 5. What is thermo-electric current?
Ans. When two wires of different materials are joined at the ends and one junction is heated, a current starts to flow. On cooling, the current starts in the opposite direction. This current is called thermo-electric current.
Q 6. What is an arc lamp?
Ans. When two rods of carbon, close together, are connected to the terminals of a powerful battery, a current flows through the junction. If the ends are now separated, sparks pass between the tips of the carbon rods. The shape of the sparks is like an arc of a circle. They become incandescent; this source of bright light is the carbon arc.
Q 7. What is an Atomic Reactor?
Ans. It is an apparatus designed to permit nuclear chain (fission) reactions to occur under controlled conditions. Huge amount of (heat) energy is produced in a controlled manner. It is employed for the manufacture of radio-isotopes, for carrying on research on the peaceful uses of atomic energy, and generating electricity-
Q 8. What is a breeder reactor?
Ans. It is a kind of nuclear reactor which besides producing energy by the fission process also produces (breeds) more nuclear fuel simultaneously.
In a typical reaction, a neutron induces fission of a U- 235 nucleus which breaks up its two medium sized nuclei and some neutrons; one of the latter then enters a U-238 nucleus (U-238 is always present with U-235 in Uranium fuel) which then decays radioactively into Plutonium which again is a useful fuel and can be fissioned.
Q 9. What is the difference between a Thermal Reactor and a Fast Reactor?
Ans. In a Thermal Reactor, neutrons released in the chain reaction are slowed down using a moderator like heavy water or graphite. In a Fast Reactor, slowing down of neutrons is not required and thus light water is used. Thermal Reactors use natural uranium as fuel (a mixture of U-238 and some U-235) while Fast Reactors use enriched uranium, in which the proportion of U-235 has been increased.