Questions

W is the symbol for chemical element Tungsten or Wolfram.

It is used in making filaments of bulbs.

The Great wall is a mighty monument to the building skill of ancient China. This wall, built of stone and earth to a height of 6 metres and extending over 2400 kilometres of hills and valleys, links the east coast with the mountains of the west right across northern China. The wall was wide enough for a carriage to go through.At intervals of every few hundred metres were located watch towers for warriors. Such a large study construction must have taken decades and an army of labourers to complete it. 

23 chromosomes are in a human gamete.

Human somatic cells have 46 chromosomes(23 pairs) but a gamete(germ cell) gets half the amount, i.e. 23 chromosomes, (one from each pair). There will be half the number of chromosomes an organism has in its somatic cells (all other body cells except gametes).

For example in humans, the somatic cells contain 46 chromosomes which are the diploid number (2n) and each sperm and egg has 23 chromosomes where one of them is the sex chromosome.

In rusting the Iron ore make a chemical reaction with the oxygen in the presence of water and environmental or atmospheric moisture to produce an Iron oxide. Iron oxide is otherwise called as rust.

The rusting of iron is a chemical change because it is two substances reacting together to make a new substance.

Byzantium / Cons-tantinople/ Istanbul