Knowledge Place

Animals are useful to us in many ways. Let us look at what we get from various animals. Animals give us Milk:- Some animals like cows, goats and buffaloes give us milk. Animals give us Eggs:- Animals like hens and ducks give us eggs. Some of us eat eggs. Animals give us flesh:- Some animals like hens, goats, crabs, ducks and fish give us flesh or meat. Animals give us wool:- we get wool from sheep. Wool is used to make woolen clothes. Animals give us Leather and Silk:- We get leather from the skin of animals. Like camels. Goats, buffaloes and snakes. It is wrong ti kill animals for leather. We should only use the skin of dead animals to get leather. Silkworms give us silk fibers:- Silk fibers are used to make silk clothes. Animals Make our Work easy:- some animals make our work easy. Elephants, camels, horses and donkeys carry load for us. They are also used to carry us from one place to another. Oxen plough our fields. Other useful animals:-...

Temporary Houses: Some houses can be moved from one place to another. Such houses are called temporary houses. 1) Houseboat:- A houseboat is a floating house. Tourists visit Kashmir to enjoy their stay in houseboats. 2) Wheel Caravan:- Some people move from one place to another in search of food and water. They are known as nomads or khanabadosh. Such people live in houses on wheels called wheel caravans. 3) Tent : - Some houses are made of canvas (Cloth). They are called tent. They can be folded easily and carried along. They are very easy to put up. Such tents are used by mountaineers and campers. Special Houses:- Some houses are made according to the place where they are located. 1) Igloos:- Some people live in houses made of snow. These houses are called Igloos. Such houses are made in areas where it snows a lot. 2) Stilt House:- Stilt houses are made in areas that are generally folooded due to rain. A stilt hose stands on a set of wooden posts. It is quite high above the ...

Heart, brain, stomach and lungs are important internal organs. They are inside our body. Brain:- The brain is inside our head. It helps us to think, learn and remember. It controls all the organs of the body. Heart: Heart pumps blood to all parts of the body. Lungs: There are two lungs inside our chest. These lungs help us to breathe. They are filled up with air when we breathe in. Stomach:- Where does the food go after we eat and swallow it? It goes into our stomach. The stomach digests the food we eat. Bones and Muscles:- Our body is made of bones and muscles. Bones and muscles work together to make us move, run and play.

As it is evident from the reactivity series of metals, silver and gold are the least reactive metals. They do not react with air, water, acids, bases and other substances. So they occur in free state in nature and are known as noble metals. Platinum shows the similar properties and is also a noble metal. A silver gold and platinum are highly malleable and ductile metals; they can be drawn into extremely thin wires and can be batten into thin sheets and foils. Because of this reason they are used for making jewellery. Gold is also used for plating other metals such as copper and silver. Platinum is used in dentistry and in making scientific instruments.

Uses of common non metals: Phosphorus is used in matchbox industry and for making fertilizers. Iodine is used as an antiseptic for dressing wounds. Nitrogen is used in the manufacture of fertilizers for the growth and development of plants. Urea and calcium ammonium nitrate are commonly used fertilizers. Nitrogen is also used to preserve food materials due to its inertness.’ Hydrogen is used in the manufacturing of ammonia. Liquid hydrogen is used as a rocket fuel. Silicon is used for making microchips which are used for making different kinds of electronic goods. Oxygen is essential for all living beings for respiration. Sulphur is used for making fire crackers, gun, poder, sulphuric acid and in vulcanization of rubber to make it hard enough to be used in tyros. Chlorine is used as a disinfectant to clean drinking water. Graphite is used in batteries and for making lead of pencils. Diamond is used for making jewellery and in cutting and grinding tools.

Both metals and non metals exhibit physical properties. Some of them are- Physical State:- all metals are generally solid at room temperature, except mercury and gallium which are liquid at room temperature. Iron, copper, aluminum, gold, silver are some of the examples of metals. Non Metals may be solid liquid or gases at the room temperature. Carbon sulphur and phosphorus are solid non metals bromine is a liquid non metal whereas hydrogen, oxygen, nitrogen and chlorine are gaseous non metals. Hardness and Strength:- Many metal are found to be hard and strong such as iron, copper etc. some are so soft that they can be cut with a knife such as sodium and potassium. None metals are generally soft. However diamond is the hardest naturally occurring substance. Luster:- Metals are lustrous , that is they have a shining surface and can be polished. Non metals are not lustrous nor do they have a shiny appearance except iodine and graphite which are lustrous is appearanc...

Metals:- metals are the elements that conduct heat and electricity and are malleable and ductile. Sodium, potassium, calcium, magnesium, aluminum, zinc, iron, tin, lead, copper, silver, gold are some of the examples of metals. On the basis of chemical reactions metals can also be defined as the elements which form positive ions by losing electrons. Non-Metals:- non metals are the elements that do not conduct heat and electricity and are neither malleable nor ductile. They are brittle. Hydrogen, oxygen, nitrogen, carbon, sulphur, phosphorus, chlorine, bromine are some of the examples of non metals. On the basis of chemical reactions, non metals can also be defined as the elements which form negative ions by gaining electrons.

Plastics can be moulded in any shape. The word plastic is derived from the Greek word ‘plastikos’ that means “capable of being shaped” or “moulded”. Plasticity is the property of plastics that allows it to be moulded into any shape or form. Almost all the items of daily use such as buckets, comb, furniture, bottles, and lunch boxes are made of plastic. The plastic can also be formed by linear or cross polymerization. Types of Plastics:- 1. Thermoplastics 2. Thermosetting Plastics Properties of Plastics:- They do not get corroded. They are non reactive to water and air. They can be used to store chemicals. They are resistant to bacterial action. They are inflammable so they burn easily. They are light in weight. They are easy to store. They are inexpensive. They are poor conductors of electricity. They are poor conductors of heat. Uses of Plastics: Polythene- Polybags, packing food items such as milk and juices, shopping bags etc. PVC – Outer covering of electrical wires,...

Food can be prevented from spoilage by microorganisms in a number of ways. Prevention of food from getting spoiled using different methods is called food preservation. Drying of dehydration:- Since microorganisms grow in moist conditions it is important to dry the food items like seeds before storing them. Removing moisture or extra water content . Many vegetables and seeds are dried in the sun to remove moisture from them. Sweetening and Salting:- Addition of sweet and salt to food items helps in losing water from them. Sweetening is used to make jams, jellies and squashes. Salting is used to prepare pickles, sauces and purees. Fish, meat and chips are also preserved by salting. Heating:- Heating food items to high temperatures kills microorganisms. Milk is preserved using the technique called pasteurization. In this process milk is first heated to very high temperatures and they cooled rapidly to very low temperatures. This heating and rapid cooling kills the microorganisms. The ...

Microorganisms cause many diseases in humans, animals and even plants. They can enter the body of the host organism through different modes such as air, water, food, insect’s cuts and wounds and direct contact. All these modes are called modes of disease transmission. The microorganisms that cause diseases are called pathogens or germs. The diseases that can spread from one person to another are called communicable diseases. Cold and cough, tuberculosis, cholera and malaria are some examples of the communicable diseases that get transmitted through different modes of transmission.   Diseases in Human Beings: Through Air:-   Could and cough and tuberculosis are the examples fo some diseases that can get transmitted from an infected to a healthy person through air. The pathogens of these diseases enter the air when the infected person coughs or sneezes. The healthy person who breathes the infected air also suffers from the disease. Through insects:-   The diseases t...

Microorganisms play a vital role in making medicines. They are used to make different antibiotics and vaccines to combat deadly diseases. Antibiotics: Antibiotics are the most commonly prescribed medicines to cure microbial diseases in plants, humans and animals. Microorganisms like bacteria and fungi are used to make antibiotics that are used to cure a number of diseases. The famous scientist, Alexander Fleming discovered that pen cilium, a fungus, can be used to cure diseases. Therefore, streptomycin and tetracycline antibiotics. Vaccines: our body has a natural defense action when a microbe enters our body; it produces special disease-fighting substances called antibodies. The disease a using microbe is called antigen. Therefore, every time an antigen enters our body, it fights back by producing antibodies; these antibodies remain in our body and fight diseases in the future. Vaccines contain dead or weakened microbes. When a vaccine is injected or swallowed, our body produces an...