Questions

The atmosphere is a mixture of several gases. Nitrogen is the most abundant gas in the atmoshere and oxygen is next to it. It is 78% in the atmosphere and 21% is oxygen. Remaining 1% is all other gases like argon, hydrogen, neon, etc...

synchronous motor can operate at lag lead and unity power factor also why because it is mainly depends on excitation

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. 

Yes, plant cells have Mitochondria.

While plant cells have chloroplasts to photosynthesize, they also require ATP for cellular functions, and do use oxygen to break down some of the sugar they produce in order to generate that ATP. They need mitochondria for this.

In particular, at night when there is no light, plants undergo cellular respiration since there is no sunlight to photosynthesize.

They do, however, produce far more sugar and oxygen through photosynthesis than they use up in respiration.

A data structure is a specialized format for organizing and storing data. General data structure types include the array, the file, the record, the table, the tree, and so on. Any data structure is designed to organize data to suit a specific purpose so that it can be accessed and worked with in appropriate ways.

Linear data structure: A linear data structure traverses the data elements sequentially, in which only one data element can directly be reached.

Ex: Arrays, Linked Lists, Stack, Queue, Any type of List all are linear.

Trees like Binary Tree, B Tree or B+ Tree are examples of non linear data structure.

A battle was fought between Iran under the king Darius and the state of Greece in 490 B.C at Marathon near Athens. This battle is known as the 'Battle of Marathon' in World History.