Science-6

Science-6

No. Question Answer 751 Why do earth and other planets revolve around the sun? Sun's gravitational force keeps the planets in a fixed orbit. 752 Name the unit in which electric current is measured? Ampere. 753 Which planet in the solar system moves faster around the sun than any other planet? Mercury. 754 What are antibiotics? How do antibiotics help in curing diseases caused by bacteria? In nature, there are moulds and bacteria that attack other organisms in order to obtain nourishment and to reproduce. Antibiotics are chemical substances produced by organisms (usually microorganisms) that are harmful to other bacteria and life forms. If you moisten a piece of stale bread and keep it in the open, there will be a greenish growth on it a little later. That is because of the spread of a mould called Penicillium Notatum. It produces penicillin. Penicillin is a highly effective antibiotic. Most bacteria double every half an hour. Just one bacterium (singular of bacteria) becomes thousands within a few hours. An antibiotic does not permit the multiplication of bacteria. In many cases, the antibiotic does not permit even the survival of bacteria. 755 Which is the star closest to our earth, after the sun? ProximaCentauri. 756 Who founded the school of mathematics at Alexandria in Egypt? The Greek mathematician Euclid around 300 B.C. 757 What are the remains of animals or plants, preserved deep under the earth or in rocks, etc called? Fossils. 758 The intensity of which insect's song gives us an indication of the temperature? The cricket. 759 What was the name of the first Atomic Reactor built by India? Where is it? Apsara, in Mumbai. 760 Which are the only planets to revolve clockwise around the sun? Venus and Uranus. 761 What is the study of water with reference to its occurrence in nature known as? Hydrology. 762 How can gargling with salt water help relieve a sore throat? An infection of the throat spreads rapidly. Quite a few varieties of bacteria double every half an hour. Gargling with warm water does not kill these bacteria, but it prevents their growth. Temperatures of more than 40 degrees Celsius are not conducive to the growth of bacteria. Any solution which has more than eight per cent salt inhibits the growth of bacteria. Thus, if you gargle with warm salt water, it will prevent the proliferation of bacteria. 763 Why does the sound of water keep changing when a vessel is being filled under a tap? Sound is produced by the movement of columns of air. Strike a stainless steel glass with a spoon. A sound is produced. Stop the vibration of the steel glass with your fingers. There will be no sound. When water is being filled in a vessel, sound is produced because of the movement of the column of air. This column becomes smaller and smaller as the water level rises in the vessel. Hence the sound changes. 764 What is the form in which iron is found in nature? Iron Oxide. 765 Who invented the Dynamo? Michael Faraday. 766 How does a cricket produce the chirping sound? By rubbing its legs against one of its front wings. 767 What is magma made of? Molten rocks. 768 Who first introduced the concept of molecules? Amedeo Avogadro in the year 1811. 769 From the bark of which tree is quinine extracted? Cinchona. 770 Where do frogs usually live in the hot season? Buried at the bottom of ponds. 771 Who discovered Calcium? Sir Humphry Davy. 772 Which is the most abundant metal in the earth's crust? Aluminium. 773 What is matter made of? Matter is made of electrically charged protons, found in the nucleus and electrons travelling about the nucleus. In addition, there are neutrons in the nucleus with a weight similar to protons but lacking any charge. 774 Who first introduced vaccination in medical practice? Edward Jenner. 775 Name the only two poisonous lizards in the world The Gila Monster and the Beaded Lizard. 776 What is the scientific study of the earth's crust known as? Geology. 777 Name the mammals that lay eggs. Platypus and Echidna. 778 Why did Galileo come into conflict with the church? Because he supported the Copernican theory that the planets (including the earth) revolve around the sun. 779 What does U.F.O stand for? Unidentified Flying Object. 780 Which is the brightest star in the sky at night? Sinus. 781 What method of healing is also known as shiatsu? Acupressure. 782 What is Hypothermia? It is a body condition in which the temperature falls suddenly as a result of exposure to extreme cold. 783 What is the thin flap of cartilage attached to the base of the tongue of terrestrial vertebrates called? Epiglottis. 784 What is the term used to describe the remains of forests where the trees have been submerged or buried and the tree tissues have been replaced gradually by minerals such as silica or calcite? Petrified Forest.