For us, the commonly accepted average body temperature is 98.6 °F (even though it may vary among individuals). Most other mammals range from 97 °F to 103 °F; birds have an average body temperature of 105 °F. Cold-blooded animals do not maintain a constant body temperature. The Pompeii worm is the world's most heat-tolerant multicelled creature, able to withstand temperatures above 176°F (80°C).

The kaleidoscope is an instrument or a toy containing inclined plane mirrors which produce multiple reflections of coloured glass pieces and create beautiful patterns. The coloured glass pieces act as objects and the inclined plane mirrors form multiple images of these glass pieces by repeated reflections, which look like beautiful patterns or designs.

To make a kaleidoscope, take three rectangular mirror strips about 15 cm long and 4 cm wide each and join them together to form a prism. Fix them in a circular cardboard tube or tube of a thick chart paper. Close one end of the tube by a cardboard disc having a hole in the centre, through which you can see. To make the disc durable, paste a piece of transparent plastic sheet under the cardboard disc. At the other end, touching the mirrors, fix a circular plane glass plate. Place on this glass plate several small pieces of coloured glass. Close this end of the tube by a ground glass plate. Allow enough space for the colour pieces to move around.

Kaleidoscope is ready to use. When we peep through the hole, we will be able to see a variety of patterns in the tube. Interesting feature of a kaleidoscope is that we never see the same pattern again. Designers of wallpapers and fabrics and artists use kaleidoscopes to get ideas for new patterns.

Hermaphrodites can either reproduce by virtue of self-fertilization or they can mate with a male and use the male derived sperm to fertilize their eggs. While virtually the entire progeny that is produced by self-fertilization is hermaphroditic, half of the cross-progeny is male. Snakes usually reproduce once or twice a year –some snakes produce live young, and some snake species lay eggs. An interesting fact about reproduction in snakes is that they usually reproduce sexually but are also capable of reproducing asexually.

Uses of Metals:
i.    Iron, copper and aluminium metals are used for making cooking utensils.
ii.    Copper is used in making electrical wires for household wiring, electric motors, etc.
iii.    Aluminium foils are used for packaging medicines, chocolates, food items and many other materials.

Uses of Non-metals:
i.    Oxygen is used by plants and animals including human beings for breathing.
ii.    Nitrogen is used in making fertilisers to enhance the growth of plants.
iii.    Chlorine is used in water purification.

For increasing friction the iron chains are wrapped on the tyres of trucks in icy areas which increases the grip and increase friction which helps the car to stop after apply breaks in icy areas. Because the smooth or icy surface reduces friction that is why if we apply breaks the truck does not stops.

Chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products.

Silver plating is a process in which the object which one to be plated (e.g. spoon) is from the cathode of the electrolytic cell. The anode is bar of silver metal,the electrolyte is a solution silver cyanide, AgCN, in the water. Thus, anode bar gradually dissolved to replenish the silver ion in the solution.

Galileo Galilei, Sir Isaac Newton, and Albert Einstein have all been called fathers of physics.

A device having or operating with components such as microchips and transistors that control and direct electric currents is called an electronic.

The electroscope is a device for detecting electric charge on an object.

An electroscope has a brass rod passing through a tight fitting cork in a glass bottle. A pair of thin aluminum leaves is attached to the lower end of the brass rod. To protect the aluminum leaves from external electric charge the lower half of the bottle is lined with tin foil which is ‘earthed’ by connecting it to the table.

When a charged rod is touched to the metal disc, the charge is transferred to the aluminum leaves and they diverge.

Polyester is a synthetic fibre made up of many repeating units of esters. Example – Terylene is popular polyester.

Nylon 6 is made from one monomer which has 6 carbon atoms whereas Nylon 6,6 is made from 2 monomers with each one having 6 carbon atoms . Nylon 66 is synthesized by polycondensation of hexamethylenediamine and adipic acid. Equivalent amounts of hexamethylenediamine and adipic acid are combined with water in a reactor.

Rayon is regarded as artificial silk. Rayon is a man-made fibre prepared from a natural raw material called cellulose by chemical treatment. It is obtained by the chemical treatment of wood pulp.

Physical properties of metal

• Metals are solid except mercury that is found in liquid state at room temperature.
• They are hard and tough except sodium and potassium that can be cut with a knife.
• They are lustrous i.e. they shine in light because metals possess free electrons that vibrates on getting in contact with light.
• They have high melting points except caesium and gallium have very low melting point.
• They are good conductors of heat and electricity. The best conductors of electricity are silver and copper whereas lead and mercury are comparatively poor conductors.
• They have high density except alkali metals like lithium, sodium and potassium.
• They are malleablee. they can be beaten into thin sheets. For instance, the aluminium foil we use to pack food is manufactured by beating the aluminium metal into thin sheets. This a characteristic property of metal.
• They are ductilee. they can be drawn into wires. For instance. We all are familiar with copper and aluminium wires. It is due to their characteristic property of ductility that these metals can be drawn into wires.
• They are sonorouse. they produce a ringing sound when struck against a hard object. For instance, your school bells are made of metal that produces a ringing sound after the period is over when struck hard by a hammer.

The process of reproduction is not essential for the survival of an individual but reproduction is essential for the continuation of a species.
•   Modes of Reproduction:
Like plants, animal also reproduce by (i) Sexual reproduction and (ii) Asexual reproduction.

The process of reproduction is not essential for the survival of an individual but reproduction is essential for the continuation of a species.
•   Modes of Reproduction:
Like plants, animal also reproduce by (i) Sexual reproduction and (ii) Asexual reproduction.

When an object rolls over the surface of another object, the resistance to its motion is called rolling friction. Rolling friction is much less than sliding friction because an object rolls over the surface of another object.

Electroplating is basically the process of plating a metal onto the other by hydrolysis mostly to prevent corrosion of metal or for decorative purposes. The process uses an electric current to reduce dissolved metal cations to develop a lean coherent metal coating on the electrode. Electroplating is often applied in the electrical oxidation of anions on a solid substrate like the formation of silver chloride on silver wire to form silver chloride electrodes.

Electroplating is majorly applied to modify the surface features of an object (e.g corrosion protection, lubricity, abrasion), but the process can also be used to build thickness or make objects by electroforming.

We all know that in space there is no medium in which sound can travel . There is no solid , no liquid and no gas . So , on moon we cannot hear any sound . Therefore , astronauts communicate to each other by signals or microphones in space even they are more closer.

A meteoroid is a small rock composed of metal in outer space. They are significantly smaller than asteroids with size ranging from a millimetre to a meter wide. When meteoroids enter the atmosphere of earth, they eventually vaporize completely and might never reach the surface. They burn during descent and creates a light trail. Meteoroids are harmless but meteors in larger size tend to explode in the atmosphere can create shockwaves and can cause problems.

Hoarfrost, deposit of ice crystals on objects exposed to the free air, such as grass blades, tree branches, or leaves. It is formed by direct condensation of water vapour to ice at temperatures below freezing and occurs when air is brought to its frost point by cooling.