Our earth is surrounded by a layer of gases which is known as the atmosphere. It is mainly composed of  78% Nitrogen, 21% Oxygen, 1% Carbon dioxide and other gases. They are essential for life in the following ways:
(i) Required in various forms to maintain the fertility of soil.
(ii) Help plants to grow which provide us food.
(iii) Carbon dioxide helps plant to manufacture food in the presence of sunlight.

Determining the size of the Universe is a hard job. Even the most advanced instruments, which allow astronomers to observe galaxies 10 to 12 billion Light Years away, give no clue to what lies beyond the distance. The Universe is limitless.

The two Houses of the Indian Parliament are the Rajya Sabha and Lok Sabha.

Judaism constitutes the religious doctrines and a rite of the Jews as enjoined in the laws of Moses. Judaism is based on Zoroastrianism. It has given rise to two great religions of the world which are Christianity and Islam.

It is important to study about our past as it gives a lot of information regarding the political, social, economic and cultural life of the people in the earlier days. By studying about our past:
(i) We can find out about the eating habits, the clothing and housing pattern of the people of the earlier times.
(ii) We can gather information about the lives of hunters, farmers, merchants, priest, craftsmen, musicians, poets and scientists.
(iii) We can learn about the lives of children, the songs they sang, the plays they saw, the games that they played and the kind of toys with which they played.

In Rig-Vedic society, raja enjoyed highest position with the priests. They fought war to capture man and cattle, land and water. The dasa or dasi were in the lowest position in the society.They could not perform sacrifices and spoke different languages. They were captured in wars. They were treated as the property of their owner and had to do any kind of work their owner wanted.

Hints for students
(i) Name and location of your state or Union Territory, write the name of your region.
(ii) Look carefully in the map, is any janapada site in your state/UTs.
(iii) If yes, name that janapadas.
(iv] If not, look all directions of your state (East, West, North, South).
(v) See the map

Challenges faced by rural women:
(i) Poor resource base and resource quality (small or no agricultural land and water).
(ii) Illiteracy and lack of skill.
(iii) Lack of awareness on different government schemes and programmes.
(iv) Lack of knowledge of disasters.
Challenges faced by urban women:
(i) Lack of employment and irregular jobs.
(ii) Lack of job security and low wages.
(iii)Lack of sufficient and timely credit support system for petty trades.
(iv) Fear of eviction by police and civic bodies.
(v) Congested and hazardous working conditions

There are thousands of species of animals and a large variety of reptiles, amphibians, mammals, birds, insects and worms which dwell in the forest of India.
(i) The tiger is our national animal. It is found in various parts of the country. Gir forest in Gujarat is the home of Asiatic lions.
(ii) Elephants and one-horned rhinoceroses roam in the forests of Assam. Elephants are also found in Kerala and Karnataka.
(iii) Camels and wild asses are found in the Great Indian desert and the Rann of Kuchchh.
(iv) Wild goats, snow leopards, bears, etc. are found in the Himalayan region.
(v) Besides these, many other animals are found in our country such as monkey, wolf, jackal, nilgai, cheetah, etc.
(vi) There are several hundreds of species of snakes found in India. Cobras and kraits are important among them. India is equally rich in bird life.
(vii) The peacock is our national bird. Other common birds are parrots, pigeons, mynah, geese, bulbul and ducks.
(viii) There are several bird sanctuaries which have been formed to give birds their natural habitat. These provide the birds with protection from hunters.

(i) The members of the Lok Sabha are elected directly by the people.
(ii) Territorial areas called Parliamentary Constituencies are set up in each State and Union territory for the purpose of elections.
(iii) Seats are allotted to various States on the basis of their respective population.
(iv) Any number of candidates may contest an election from the same constituency.
(v) The candidate who secures majority of vote is declared elected to the Lok Sabha.

(i) The Ashvamedha or horse sacrifice was one of the rituals. In this, a horse was let loose to wander freely and it was guarded by the Rajas.
(ii) If the horse wandered into the kingdoms of other Rajas and they stopped it then they had to fight.
(iii) If they allowed the horse to pass, it meant that they accepted that the Raja wanted to perform the sacrifice and was stronger than them.
(iv) These Rajas were then invited to the sacrifice, which was performed by specially trained priests. The Raja that organised the sacrifice was recognised as very powerful.

The farmers and herders in the earlier period cultivated the fields themselves and domesticated the animals. The farmers and herders who gave food to the Harappan cities knew about agriculture and domestication of animals. So, they supplied food to the city dwellers and they also provided their own food.

(i) Asia with 44 squares is the largest continent.
(ii) Europe (10 squares) is larger than Australia (8 squares).