Language and the popular tradition is a key representation of a national identity. A person is known by these two features in a foreign land. Every nation has its own mode of communication, culture and traditions. And when a person go abroad then he represents his nation by these two characteristics. For example Chinese don't believe in learning new languages rather they are endeavoring to promote their own language. Often they take translators with them on visits to other countries. Then same is the case with tradition. Then in India they traditions are so fascinating that other countries imitate their traditions like Diwali etc.

DNA is a group of molecules that is responsible for carrying and transmitting the hereditary materials or the genetic instructions from parents to offsprings.

DNA was first recognized and identified by the Swiss biologist, Johannes Friedrich Miescher in 1869 during his research on white blood cells.

The double helix structure of a DNA molecule was later discovered through the experimental data by James Watson and Francis Crick. Finally, it was proved that DNA is responsible for storing the genetic information of a human being.

1000 milliamperes makes 1 ampere
So, 20000 milliamperes makes 20 ampere

Exchange of gases takes place between the alveoli of lungs and the surrounding blood capillaries.  The two main gases exchanged are oxygen and carbon-dioxide. Oxygen is absorbed by the blood capillaries from the lungs alveoli by diffusion while carbon dioxide is absorbed by the lungs alveoli from blood capillaries by diffusion. Transport of oxygen and carbon dioxide occurs with the help of respiratory pigment called hemoglobin. Haemoglobin, the iron-containing respiratory pigment is a red coloured pigment of blood, which has a very high affinity for oxygen. Haemoglobin though is purple coloured but oxyhemoglobin is of bright red colour. Oxygen is transported from lungs to the body cells in the form of oxyhemoglobin. Carbon dioxide is transported from the body cell to the lungs in the forms of carboxyhemoglobin, carbonic acid, bicarbonates of sodium and potassium.

According to this classification, labour, capital, land or natural resources, technology, management etc., are considered economic factors and culture, religion, tradition etc. non-economic factors. There is still an ambiguity about the situation of knowledge - which has an important role in economic development.

Development is a process such that the rate of increase in national income is more than the increase in population. It is the betterment in the lives of the people and also rise in living standards of the people.

Characteristics of development

(i) Different people have different developmental goals.

(ii) What may be development for one may not be development for the other. It may be destructive for the other.

(iii) Income is the most important component of development, but along with income, people also seek equal treatment, good health, peace, literacy, etc.

(iv) For development, people look at mixed goals.

It would be hard to imagine an economy developing without oil and natural gas, because it is the basis of every industrialized economy on Earth right now.

Crude oil provides 97% of the energy for transportation (cars, trains, airplanes) in the world. In the US, oil and gas make about 20% of the electricity. In addition to that, think of all the things we make from oil:

- plastics: just look at all the things made of plastic in front of you right now!

- lubrication oils

- petrochemicals for fertilizer, paint, preservatives, pharmaceuticals, cleaning chemicals, etc

-fabric: most synthetic fabrics are based on petrochemicals

So, try to imagine a country without all of these things. This would place you back in time more than 100 years in terms of technology.

Neutralization is a chemical reaction in which acid and base combine to form salt and water. Acids donate H⁺ and bases donate OH^-  in water which combine to form water molecules.

Example
HCl + NaOH---NaCl + H₂O
and HNO₃ + KOH---KNO₃+ H₂O

Variations arise in organism by:
The phenomenon is the passing of genes and heredity.

Variation occurs when one gene in the organism is mutated.If it allows the organism to survive longer than the others in the population without the mutation, it gives the mutated organism a higher chance to pass on its genes. When these genes are passed on, their kids may have the mutation but they will carry the mutated gene. As long as this helps the organism survive it will continue to be passed on to the next generation. After many generations, the mutated trait becomes common which means they have evolved.

Example- For example, a population of long beaks inhabit a particular area. Now, the food can be consumed properly with short beaks. If due to some variations, there may be a possibility that there are some birds with short beaks in that population. So, in the new area, they will survive better and reproduce more which will lead to the evolution of more and new species.

II. Variations is useful for the survival of species because:

1. Variation acts as a source of raw material for evolution of species.

2. Variation leads to genetic diversity, which is a key for the evolution of species. Animals are able to adapt themselves to the changing environment by inheriting some of the beneficial variations. Organisms are better suited to face the struggle for existence due to the presence of variations.

3. Variations give the species an individuality of their own. In the absence of variation, there would be no science of heredity as all individuals of a race, would be identical to one another in all aspects.

All the variants, however, do not have equal chances of survival. Depending on the environmental conditions, the nature favours only those variants that are able to adjust to the changing environment. The theory of natural selection favours the survival of the fittest. 

Salts are ionic in nature due to the presence of ions. They are brittle, hard and crystalline solids. Salt is white, odorless and it has a salty taste. All potassium (K), ammonium (NH4+) and sodium (Na) salts are soluble in water (H2O). Common salt is obtained from sea-water by the process of evaporation. Sea water is trapped in large, shallow pools and allowed to stand there. The sun's heat evaporates the water slowly and common salt is left behind. Used as a preservative in pickles and in curing meat and fish. Used in the manufacture of soap. Used to melt the ice in winter in cold countries. Used for making chemical likes washing Soda, baking soda etc.

The term sustainable development is applied to the development of a country or world, that is to resume and maintained for future generations. For instance, groundwater; it is generally rendered by nature. Accordingly, we must consume groundwater in a manner that it can be said a Rational or careful use of resources. Moreover, the precise and systematic use of groundwater is essential as imprudent use of the naturally provided (groundwater; in the case of groundwater) resources may deplete them. We should not consume and contaminated the groundwater to a degree that it converts unavailable or unusable for our forthcoming generation.