On burning candle wax melts and vaporise to burn and give heat and light.

roasting

If the ignition temperature of a substance (minimum temperature at which a substance catches fire) is lower than the room temperature then it will burn spontaneously i.e. no external substance is required to burn the fuel.

This kind of combustion is known as spontaneous combustion.

Plz tell me a short answer itz very long plz

Candles really are an amazing lighting system -- the fuel itself is the package. There are two parts that work together in a candle:

• The fuel, made of some sort of wax.
• The wick, made of some sort of absorbent twine..

The wick needs to be naturally absorbent, like a towel, or it needs to have a strong capillary action (as in glass fiber wicks used in oil lamps). If you buy a length of un-waxed wick at a craft store and play with it, you will find that it feels like soft string and absorbs water very well. This absorbency is important in a candle because the wick needs to absorb liquid wax and move it upward while the candle is burning.

The fuel that burns without giving out water vapour is coke which is a pure form of carbon. It has high carbon content and low amount of hydrocarbon.

Normally water vapour is given off when there is presence of hydrogen in a given fuel and as coke have very low hydrogen content. Therefore water vapour is not given out .

Itsimply burns with the evolution of carbon dioxide.

{tex}C+O_2 \ \to CO_2{/tex}

A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years. Fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas. Since most of the vehicles today operate on these fuels( fossil ones), it is said "Fossils in our cars". It simply refers to the use of fossil fuels to run our vehicles.

Rayon, a man made fibre is made from cellulose obtained from wood pulp. Due to presence of "cellulose acetate",it is lustrous.

Increasing crops affect the environment as for the production of crops various pesticides and fertilisers are required which may alter the quality of the environment

Vector quantity is that quantity in which a body has both magnitude as well as direction. A vector has more than one number associated with it Like velocity, 

A vector quantity is a quantity of something which possesses both magnitude and direction. Magnitude is simply the size or amount of the quantity. For example, the magnitude of the quantity eight miles per hour is eight. Direction is meant in the ordinary sense, where the quantity is headed.

The magnitude of frictional force or drag exerted by a fluid on an object moving through it is directly proportional to speed of the object.

Higher the speed of an object moving to a fluid ,greater will be the frictional force acting on it .

Frictional Force refers to the force generated by two surfaces that contacts and slide against each other.

These forces are mainly affected by the surface texture and amount of force impelling them together.

The angle and position of the object affect the amount of frictional force.

• Reuse
• Reduce
• Recycle

Nylon  is the first synthetic fibre. It is a polyamide fibre, containing many amide units repeated to form a long chain . Amides are a class of chemicals which are also present in protein.

Ethene 

Animal husbandry is the practice employed to increase the production of animal products by livestock. Animal husbandry includes feeding, breeding, and disease control of livestock animals.

Ans. Hydrogen and Oxygen (air under normal laboratory conditions) when mixed together form an explosive mixture.  So, when a burning splinter is brought near the gas mixture - it explodes.

Since the amount of gas is very small only a tiny pop sound is produced. This in turn extinguishes the splinter. If a larger amount of hydrogen is taken a massive explosion can take place.

Ans. The preparation of soil is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil.

The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it
. 
Soil contains minerals, water, air and some living organisms. In addition, dead plants and animals get decomposed by soil organisms. In this way, various nutrients held in the dead organisms are released back into the soil.

Since only a few centimetres of the top layer of soil supports plant growth, turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients. Thus, turning and loosening of soil is very important for cultivation of crops.

The process of loosening and turning of the soil is called tilling or ploughing. This is done by using a plough. 

Ans.
1. Generally metals are hard. Exception – sodium and potassium. It is so soft that it can cut with a knife.
2. Metals are found in solid state. exception – mercury exists in liquid state.
3. The boiling point and melting point of metals are high. Exception – sodium and potassium. Gallium cesium
4. Metal has high density. Exception – sodium and potassium.
5. Metals are sonorous. Exception – Mercury
6. Metals are malleable. Exception – Mercury
7. Metals are ductile. Exception – mercury.

Microbe is a term for tiny creatures that individually are too small to be seen with the unaided eye. Microbes include bacteria, archaea,fungi and protists.

COAL

We will give time to microbes to act on the soil and make it fertile again

Natural polymers are silk, wool, cellulose

Artificial/ synthetic polymer are nylon, polythene, polyster, teflon

Monomers vinyl chloride polymerize into PVC, glucose into starch

The process of growing different kinds of crop in different seasons in a particular plot of land to avoid exhaustion of fertility is known as rotation of crops. 

no, only real image can be obtained on screen

Noo

Ans. Strength of class 2 years ago = 70000

Decreasing rate = 10%

Strength after 1 year = {tex}70000 - {70000\times 10\over 100} = 70000-7000{/tex}

= 63000

Present Strength = {tex}63000-{63000\times 10\over 100} = 63000-6300{/tex}

=56700

Movement of body in its fix axis by the moving object to and frocalled oscillation.

To and fro movement of a body around fixed axis is called oscillation.

a)

Sodium Zeolite is a a white powdery substance with a cubic crystal structure. ... Because Sodium Zeolite is a mineral, its chemical composition can vary somewhat. Average chemical composition of sodium zeolite is reported as Sodium Oxide - 17%, Aluminum Oxide - 28%, Silicon dioxide – 33% and water – 22%. ¹.

Antifreezes such as ethylene glycol or propylene glycol commonly added to water in automobile cooling systems prevent damage to radiators.

They are a mixture of alcohols and are water based.