The biogas plant consists of a dome-like structure. Organic material such as discarded food residue, fats, sludge, cow dung etc. are mixed with water and fed to the digester through the inlet as shown in the figure.

The digester is a sealed chamber where anaerobic decomposition of organic matter takes place. After a few days, the organic matter completely decomposes to generate gases like methane, carbon dioxide, hydrogen and hydrogen sulphide. These gases are then drawn through pipes from the storage tank above the digester and distributed through decentralization channels to nearby centres for use.

- After a failed round table conference, Gandhiji launched the civil disobedience movement.
- In retaliation by the British government,  Indian leaders were arrested, angry crowds demonstrated in the streets of Peshawar, facing armoured cars and police firing.
- Hundreds of people were killed.
- A month later, Gandhiji himself was arrested, industrial workers attacked police posts, government buildings, law courts and railway stations and various structures that were directly working for the British rule.
- Even the peaceful satyagrahis were attacked, women and children were beaten, and about 100,000 people were arrested.
- To break the deadline between Congress and the government Lord Irwin invited Gandhiji for a peace pact that was called Gandhi—Irwin pact.
- As a consequence to the above reasons, Gandhiji decided to call off the movement .

Serbia, Greece and Bulgaria were under Turkey which was called the Ottoman Emperor.

These states wanted independence because of despotic rule of Turkey due to the right of nationalism.

Islams made the Christians their victims. So, there was frequent war to the Balkan region. So, to initiate the first word war, Balkan countries were also responsible.

The immediate cause of the First World War was:

Assassination of Archduke Franz Ferdinand the prince of Austria-Hungary) and his wife by a member of black-hand group.

Austrian government declared war against Serbia on 28th July 1914 and initiated the destructive and enormous the First World War.

The Khilafat Movement was launched by Muhammad Ali and Shaukat Ali. Gandhiji saw this as an opportunity to bring Muslims under the umbrella of a unified national movement. At the Calcutta Session of the Congress in September 1920, he convinced other leaders to start a Non-Cooperation Movement in support of Khilafat Movement.
The Khilafat Movement (1919-1924), was a pan-Islamic, political protest campaign launched by Muslims in British India to influence the British Government and to protect the Ottoman empire during the aftermath of First World War. The First World War had ended with the defeat of Ottoman Turkey.
There was a fear that the power of the spiritual head of the Islamic world (Khalifa) would be curtailed. To defend his power, a Khilafat Committee was formed in Bombay in 1919. The Khilafat leaders put pressure . upon the British Government to give better treatment to Turkey.

Tourism can be considered as a trade because :
It involves exchange and buying/selling of products.
The products can be defined in terms of holiday packages , hotel rents, means of transport and hospitality etc.
Exchange of cultures take place and these exchanges are in monetary terms.
Foreign tourists visit India for heritage tourism, adventure tourism, cultural tourism, and business tourism and in the same manner Indians visit foreign places.
Tourism can be considered as an industry because:
Tourism is a large scale industry as the money involved in it is very high.
There is near about Rs 21,​828 crore of foreign exchange per year.
Large numbers of people are directly engaged in tourism industry, as many as 20 million people.
Promotes national integration and local handicrafts along with culture and heritage.
It has huge chances of expansion.

Economic Inequality
It means split of society between rich and poor classes.
The rich enjoy all possible facility of life and lead a very good standard of life.
Whereas the poor people even do not meet the meals of two times in a day. They are unable to fulfill even their basic necessities.
Harm of Economic Inequality
Economic inequality is harmful for the success of democracy as it intensify the ego among the rich people while inferiority complex among the poor, and emotional outburst are seen in strikes, murder, decoity and class conflicts.

(i) Print was used to criticise existing practices. Through print, people could be persuaded to think differently.

(ii) Even those who disagreed with established authorities could now print and circulate their ideas. It shaped new ideas and debates and new ideas emerged from clashes.

(iii) The religious reformer Martin Luther wrote ninety five theses criticising many of the practices and rituals of the Roman Catholic Church. He challenged the Church to debate his ideas.

(iv) Muslims used print to check conversions. (v) Hindus used print to encourage people to read the religious texts in vernacular.

Concurrent List - The Concurrent List contains subjects of common interest to both the Union as well as the States. These include education, forest, trade unions, marriage, adoption and succession. The law relating to these subjects can be made by both the Central and State Governments.

a. Favourable trade balance implies when exports of a country are more than imports, that is the value of exports are more than its value of imports in a particular period of time.

unfavorable If country's imports are more than its exports, that is the value of imports exceeds value of exports, it amounts to unfavourable balance of trade.

b. . favourable exports are more than imports it amounts to trade surplus as it leads to inflow of foreign capital.

unfavorable If imports and more than exports it amounts to trade deficit.

The three main features of Rabi crop are:

1. Rabi crops are sown in winter from October to December and harvested in summer from April to June.

2. Wheat, barley, peas, grams, and mustard are examples of Rabi crop.

3. During the winter months, the precipitation from western cyclone helps in the success of these crops.

The British government arrested the two national leaders of India Dr Satya Pal and Dr Saifuddin Kitchlew for their involvement in the protests against the Rowlatt Act, which led to pervasive unrest among the people of Punjab. On April 13, 1919, on the occasion of Baisakhi, the people (men, women and children) of Punjab launched a peaceful protest against their arrest. The British military Commander General Dyer reached the park with soldiers and blocked the entrance of the park. Thereafter he ordered his soldiers to open fire. This firing lasted for ten minutes and killed thousands of people. The massacre ignited the anger of the Indians.

The painter depicted Germania as a fallen woman with the crown and standard thrown aside because German people's hopes to be united under one monarch (King Friedrich Willhelm IV) were dashed as he rejected their demand in 1848. The artist, Julius Hubner, depicted Germania in a forlorn state due to this rejection by the king. It symbolized the loss of hope. The crown and standard are symbols of the monarchy, which have been cast aside.

The differences can be gauged from the following:Caste in PoliticsPolitics in castea. When we refer to caste in politics, we refer to various forms caste can takein politics, and how this issue which is indeed a social factor gets politicised.Politics in caste, explains how politics impacts caste, it explains how various caste based groups are trying to assert their rights in their quest to acquire power and authority.b. For instance, Caste has also emerged as major vote bank factor during elections. Political parties try to muster support on the basis of casteby exploiting the caste sentiments of the people, fielding candidates of a particular caste to reach out to more and more peopleWe may give example rise of many caste based groups, forwardor backward caste groups who with the support of caste based parties, have been influencing the decisions of the government.c.With legal and political rights beingextended to the historically most marginalised community members, political parties try to expandtheir support base.We have seen rise of many caste based groups and of caste based parties, have been wielding considerable power in their respective statesand influencing the decisions of the central government.d. Caste in politics also explains how caste is an importantfactor in elections, ifnot the only factor.These groups have also entered into bargaining and negotiations among themselves for the purpose of wielding more power, The Dalits, OBC''s have acquired political consciousness pressed for reservations.

Major forms of power sharing in modern democracy are:

• Power sharing among different Organs of the Government: In democracy, power is shared among Legislature, Executive and Juduciary.This is known as distribution of power. No organ of the governemnt can e P xcercise unlimited power as each ower sharing among different Organs of the Government organ checks the others.
• Governments at different levels: In federal form of government, power is shared between the central and state governments. In India there is another lower level of government -local self government.This is called vertical division of government.
• Social Groups: Power may also be shared among different social groups such as religious and linguistic groups. In India, there are constitutional and legal arrangements whereby socially weaker sections and women are represented in the legislatures and administration.
• Division of power between political parties, pressure groups and movements: Political parties are the organisations which aim to control power by contesting elections. In a democracy, citizens have the freedom to choose among the various contenders for power. When no party gets a majority, two or more parties come together to form a governemnt. In a democracy, pressure and interest groups also have an indirect share in the governemnt's power.

In 1815, the representatives of the European powers - Britain, Russia, Prussia and Austria wanted to establish long-lasting peace and stability after they defeated Napoleon.
Thus, they drew up the Treaty of Vienna of 1815 with the intention of undoing most of the changes brought about during the Napoleonic wars and creating a new conservative order in Europe. According to this treaty:

• The Bourbon dynasty was brought back to power and France lost the territories it had annexed under Napoleon. 
• To prevent the  French evasion, a series of states were set up on the boundaries of France.
• This lead to the  setting up of kingdom of the Netherlands (inclusive of Belgium) in the north and the kingdom of Genoa (added to Piedmont) in the south.
• Prussia was given important new territories on its western frontiers, while Austria  was given control of northern Italy.
• However, Napoleon’s German  confederation of 39 states was left untouched.

(i) Dr. Bhim Rao Ambedkar was of the opinion that only political empowerment would resolve their problems of social injustice.
(ii) Due to his efforts, Dalits began organizing themselves, demanding reserved seats in educational institutions and a separate electorate that would choose the Dalit members for legislative councils.
(iii) In 1930, Ambedkar entered national politics. In the same year, he organized the Depressed Classes Association to make them politically more strong.
(iv) He was nominated as a delegate of the oppressed classes for the Second Round Table Conference. In that Round Table Conference, he clashed with Mahatma Gandhi by demanding separate electorates for Dalits.
(v) He demanded a separate electorate for Dalits. To give them political power he signed Poona Pact. The Poona Pact gave the depressed classes reserved seats in provincial and central legislative councils.