Questions

Dull means not sharp, not shining, not bright, ...

Hence, the given words are all that means the opposite of dull.

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. 

Let amount of milk removed = 2x litre
So, amount of water added = x litre
Now → (165 − 2x)/x = 5/3
x = 45 lit

Byzantium / Cons-tantinople/ Istanbul

The scientific study of rocks is called petrology, which is an essential component of geology.

Carbon monoxide is a common atmospheric pollutant in the world which is produced in combustion process in automobiles and industries. It has no smell and cannot be seen.

Ulaanbaatar is the capital of Mongolia