QUESTION: What is the difference between nuclear fission and nuclear fusion?
Bothe of these are kinds of nuclear reaction. In fission a heavy nucleus {usually uranium} splits. In fusion, light nuclei fuse comes together. Fusion produces a thermonuclear reaction and is the most powerful source of energy known. Nuclear fission is used in nuclear power stations and in atomic bombs. Fusion is used in hydrogen bombs and may one day be harnessed to provide unlimited power, using a hydrogen like fuel called deuterium found in sea water.
QUESTION: What happened at chernobyl?
In April 1986 there was a serious accident at the Chernobyl nuclear power station in Ukraine (then part of USSR). A reactor exploded and radioactivity poisoned plants and animals. Some people died. Many others were moved to new homes away from the area. The reactor sealed in concrete forever.
QUESTION: What is an isotope?
Nearly all elements have atoms of two or more different weights. Atoms that belong to the same element, yet have different weights are called isotopes. For example, hydrogen has three isotopes which are called protium,deuterium and tritium.
QUESTION: Why can a nuclear submarines stay at the sea for such a long time?
A nuclear submarine is driven by turbine engines which use steam heated by a nuclear reactor. The reactor uses so little fuel the submarine seldom has to return to port to refuel. The world's fisrt nuclear-powered submarine was the US Navy's NAUTILUS (1955). A lump of uranium fuel the size of an electric light buld provied enough energy to drive the submarine 100,000 kilometers. In 1960 USS Triton circled the worl under water in three months without refuelling.
QUESTION: What is a mineral?
Gold, silver and mercury are examples of pure elements, but most chemical elements
react with other elements so readily that they are not found singly on earth. Instead, they combine with on another as minerals. Some 3,000 minerals are known.
QUESTION: Why does iron goes rusty?
When a piece of unpainted iron or steel is left outside in the damp air, it soon goes rusty. Rust can eat into the surface of meatal objects, such as car bodies. Rust is an example of chemical reaction, or combination, between the iron in the car bodywork and the oxygen in the air. This reaction is called oxidation and produces iron oxide, or rust. A coating of paint, of of a non-rusting meatal such as chrome, prevents rust by stopping oxygen reaching the iron.
QUESTION: What is a chemical reaction?
When two or more substances are put together, they may mix, as when you mix sand and water in a bucket, but remain seperate substances. However, if a chemical reaction takes place, they may undergo a chemical change and become a different kind of substance. For example, when zinc is added to hydrochloric acid, a reaction occurs. The products are hydrogen gas and zinc chloride.
QUESTION: What is a compound?
A compound is a substance made up of two or more elements which cannot be seperated by physical means. For example, water is a compound of hydrogen and oxygen. Each water molecule is made up of two hydrogen atoms joined to one oxygen atom by invisible forces called bonds.
QUESTIONS: What are diamonds made of?
Diamond is a form of carbon. It is the hardest substance known. Natural, uncut diamonds look dull and have no lustre. The brilliant gems that are so valuable are made by careful cutting and polishing.
QUESTIONS: Which is the most abundant metal on Earth?
The metal found most plentifully in the Earth's crust is aluminum, which makes up about 8 percent of the crust. It is found not as a pure metal but as an ore called bauxite.
QUESTION: Which metals give color to fireworks?
Strontium burn with a red light, copper green, sodium yellow, barium green and magnesium a brilliant white light.
QUESTION: Why will carbon dioxide put out fire?
Carbon dioxide gas will not support combustion. Pure carbon doixide is also heavier than air. If sprayed on a fire from a fire extinguisher it forms a blanket,cutting off the oxygen which would otherwise feed the flames.
QUESTION: What is a metal?
Elements can be divided into basic group: metals and non metals. Metals can be made to shine or have a lustre, they conduct heat and electricity easily and thay are 'malleable'- they can be beaten into shape or pulled oput into wire. More than 70 of the known elements are metals.
QUESTION: What is electricity?
Electricity is a form of energy. It is produced when electrons, tiny atomic particles move from one atom to another. Although scientists had known that this mysterious energy existed, Its workings were not understood until the secretsa of the atom began to be revealed about a century ago.
Without electricity, our lives would be different. We would have no radios or televisions , no telephones, no computers. Our streets and homes would be lit by oil or gas lamps and we would have none of the gadgets that we take for granted today.
