1. The number of females per 1000 males in the population is called sex ratio.

2. According to the 2011 census, the sex ratio of India is 943. That means there are 943 women for every 1000 men.

1. Hematite is an ore of iron. It is commonly found in stones and soil. The largest quantity of iron in the earth is found in the form of hematite.

2. The chemical formula of hematite is Fe2O3. It is a heavy and relatively hard oxide mineral.

  3. Its colour ranges from black to steel or silver-grey, grey to brown or reddish.

4. Hematite is used in the production of iron. It is an important mineral that is found in many countries around the world.

Chennai Port, formerly known as Madras Port, is the second largest container port of India, behind the Nhava Sheva Port, and the largest port in the Bay of Bengal.

1. Humus is found in the topmost layer of soil (A-horizon).

2. Humus is a black or brown colored substance which makes the soil fertile.

3. It is an important source of nutrients for plants, and it helps the soil absorb water and air.

4. There are many ways to promote humus, including-

- Leaving crop residues in the field

- Using livestock manure

- making compost