side of square = 4 cm

Area of square = side ×  side = 4 ×  4 = 16 sq. cm

1) PIL of public interest litigation is an important step, ensuring access to justice for all. It allows any individual or organised action to file PIL in the High Court or Supreme Court and behalf of those whose rights has been violated .

2) The poor who are not educated enough or cannot afford to access the Indian legel system justice against exploitation .

The modern methods of irrigation help us to use water economically. The two main modern methods of irrigation are:

1.  Sprinkler system – In sprinkler system of irrigation, a main pipe is laid in the fields to which perpendicular pipes are joined at regular intervals. When water from a tube-well is allowed to flow through the main pipeline under pressure with the help of a pump, it escapes from the rotating nozzles and gets sprinkled on the crops. This method of irrigation is more useful for the uneven land and sandy soil where sufficient water is not available.
2. Drip system – In the drip system, there is a network of narrow pipes with small holes in the fields. When water falls through these narrow pipes, it falls drop by drop at the position of the roots of the plants. There is no run-off or wastage of water. This technique is the best technique for watering fruit plants, trees and gardens.

Rivers are mainly densely populated because of not only the benefit that they possess with themselves but also with the help of these river, the land gets fertile and they become the best choice for people to grow vegetables and then get their life stelled and the temperature as well as climate also remains good.

There are various methods for soil conservation such as afforestation, manuring and crop rotation, step farming, windbreaks, strip cropping, mulching. Strip cropping is the method of farming in which the field is partitioned into long, narrow strips which are alternated in a crop rotation system.

Methods of soil conservation:
Contour ploughing: Ploughing along the contour lines can check the flow of water down the slopes. 
Terrace cultivation: Steps can be cut out on the slopes making terraces. 
Strip cropping: Large fields can be divided into strips.

• Delhi initially turned into the capital of a kingdom under the Tomara Rajputs, who were vanquished by Chuahans (additionally called Chahamanas) of Ajmer.
• The change of Delhi into a capital that controlled immense range of the subcontinent
• began with the establishment of the Delhi Sultanate in the start of the thirteenth century.

Leaders of Delhi:

1. Chauhans: 1165-1192
   • Prithviraj Chauhan: 1175-1192
2. Tughlaq Dynasty: 1320-1414
3. Slave Dynasty: 1206-1290
4. Khalji Dynasty: 1290-1320
5. Tomars: Early twelfth century 1165
6. Sayyid Dynasty: 1414-1451
7. Lodi Dynastry: 1451-1526

A memo is actually short for Memorandum. It is one of the most used means of official communication in the business world. Its main purpose is to serve as a reminder or to give some instructions.

The Indian subcontinent has four important religions in the world. According to the 2011 census, Hinduism is practiced by 79.8% of India's inhabitants, Islam is adhered to by 14.2%, Christianity by 2.3% and Sikhism by 1.7%

The different ways in which religious domination is prevented by the Indian State are as follows:

• It distances itself from religion.  
• It utilizes the non-interference approach.  
• It utilizes the intervention approach .
• The Indian Constitution ensures fundamental rights based on these secular values.

Yes

1. Fuel oil: It is used in industries.
2. Petrol: It is used as a fuel in motor, aviation and as a solvent for dry cleaning.
3. Diesel: It is used as a fuel for heavy motor vehicles and electric generators.
4. Kerosene: It is used as a fuel for domestic purposes such as burning lamps, stoves and in jet aircraft.
5. Liquefied petroleum gas (LPG): It is a flammable mixture of hydrocarbon gases used as a fuel for home and in industry.

The Battle of Plassey was a major battle that took place on 23 June 1757 at Palashi, Bengal. It was an important British East India Company victory over the Nawab of Bengal and his French allies. The battle took place after the attack and plunder of Calcutta by Siraj-ud-daulah and the Black Hole of Calcutta tragedy.

We can define an even number as 2x

Let 2x be the first even number

Let 2x+2 be the next even number

Let 2x+4 be the last one

Their sum is 30 so we write

2x+(2x+2)+(2x+4)=30

Combining like terms

6x+6=30

6x=24

x=4

So

2x=2(4)=8

2x+2=8+2=10

2x+4=8+4=12

(i) Linguistic States : After independence, in 1950, the boundaries of several old states were changed in order to create new states. This was done to ensure that the people who spoke the same language, share common culture, ethnicity or geography could live in the same state.
(ii) Language Policy : The Indian Constitution did not give the status of national language to any one of the languages. Though Hindi was identified as the optional language, but the central government has not imposed Hindi on states where people speak a different language. Besides Hindi, there are 22 other languages recognised as Scheduled Languages by the Indian Constitution.
(iii) Centre-State relations : Improving the Centre-State relations is one more way in which federalism has been strengthened in practice. Though Indian Constitution has demarcated the powers of the Union and the state governments but still the Union government can have influence over the state in many ways.
In the past, the Central government has often misused the Constitution to dismiss the state governments that were controlled by rival parties. This undermined the spirit of federalism, and that of democracy.
The judiciary has played a major role in improving the autonomy of the state governments because many a time, it has rescued state governments which were dismissed in an arbitrary manner.

Friendly Microorganisms:

Microorganisms are used for various purposes by human beings as well as in nature. Some of the beneficial effects of microorganisms are as follows:

1. Microorganisms are used in the production of alcohol, wine and acetic acid.
2. They are used in making curd, bread and cake.
3. They are used in the preparation of medicines called antibiotics.
4. They are used in agriculture to increase the fertility of soil by fixing atmospheric nitrogen gas.
5. They clean up the environment by decomposing the organic matter of dead plants, dead animals and animal wastes into harmless and useful simple substances.

Microorganisms can be harmful in many ways. For example – some of the microorganisms cause diseases in human beings, other animals and plants. Such microorganisms which cause diseases are called pathogens.